diff --git a/src/shared/icons/temp_1.svg b/public/icons/temp_1.svg
similarity index 100%
rename from src/shared/icons/temp_1.svg
rename to public/icons/temp_1.svg
diff --git a/src/shared/icons/temp_2.svg b/public/icons/temp_2.svg
similarity index 100%
rename from src/shared/icons/temp_2.svg
rename to public/icons/temp_2.svg
diff --git a/src/shared/icons/temp_3.svg b/public/icons/temp_3.svg
similarity index 100%
rename from src/shared/icons/temp_3.svg
rename to public/icons/temp_3.svg
diff --git a/src/shared/icons/temp_4.svg b/public/icons/temp_4.svg
similarity index 100%
rename from src/shared/icons/temp_4.svg
rename to public/icons/temp_4.svg
diff --git a/src/app/(service)/(my)/my-study/page.tsx b/src/app/(service)/(my)/my-study/page.tsx
index d728059d..4303b0de 100644
--- a/src/app/(service)/(my)/my-study/page.tsx
+++ b/src/app/(service)/(my)/my-study/page.tsx
@@ -8,7 +8,7 @@ import { useMemberStudyListQuery } from '@/features/study/group/model/use-member
 import CompletedGroupStudyList from '@/features/study/group/ui/completed-group-study-list';
 import GroupStudyFormModal from '@/features/study/group/ui/group-study-form-modal';
 import NotCompletedGroupStudyList from '@/features/study/group/ui/not-completed-group-study-list';
-import { useAuth } from '@/hooks/use-auth';
+import { useAuth } from '@/hooks/common/use-auth';
 
 interface MemberGroupStudyList extends MemberStudyItem {
   type: 'GROUP_STUDY';
diff --git a/src/app/(service)/layout.tsx b/src/app/(service)/layout.tsx
index cd0a8fd7..8954c45e 100644
--- a/src/app/(service)/layout.tsx
+++ b/src/app/(service)/layout.tsx
@@ -43,11 +43,8 @@ export default function ServiceLayout({
         <MainProvider>
           <PageViewTracker />
           <div className="w-full overflow-auto">
-            {/** 1400 + 48*2 패딩 양옆 48로 임의적용 */}
-            <div className="m-auto flex w-[1496px] flex-1 flex-col items-center">
-              <Header />
-              <main className="w-full px-600">{children}</main>
-            </div>
+            <Header />
+            <main className="h-[calc(100vh-62px)] w-full">{children}</main>
           </div>
         </MainProvider>
       </body>
diff --git a/src/components/card/mission-card.tsx b/src/components/card/mission-card.tsx
index 935d455a..a880ece8 100644
--- a/src/components/card/mission-card.tsx
+++ b/src/components/card/mission-card.tsx
@@ -4,7 +4,8 @@ import { ComponentProps } from 'react';
 import { MissionListResponse } from '@/api/openapi/models';
 import Badge from '@/components/ui/badge';
 import Button from '@/components/ui/button';
-import { useIsLeader } from '@/providers/study-leader-context';
+import { useIsLeader } from '@/stores/useLeaderStore';
+import { useUserStore } from '@/stores/useUserStore';
 
 import DeleteMissionModal from '../modals/delete-mission-modal';
 import EditMissionModal from '../modals/edit-mission-modal';
@@ -12,6 +13,7 @@ import { cn } from '../ui/(shadcn)/lib/utils';
 
 interface MissionCardProps {
   mission: MissionListResponse;
+  groupStudyId: number;
   onSelectMission: (missionId: number) => void;
   showDeadline?: boolean;
 }
@@ -92,10 +94,12 @@ function isCardClickable(
 
 export default function MissionCard({
   mission,
+  groupStudyId,
   onSelectMission,
   showDeadline = false,
 }: MissionCardProps) {
-  const isLeader = useIsLeader();
+  const memberId = useUserStore((state) => state.memberId);
+  const isLeader = useIsLeader(memberId);
   const statusConfig =
     mission.status && mission.status in STATUS_CONFIG
       ? STATUS_CONFIG[mission.status as keyof typeof STATUS_CONFIG]
@@ -116,7 +120,7 @@ export default function MissionCard({
   // 리더 + 진행 예정: 수정/삭제 버튼만 노출
   if (isLeader && mission.status === 'NOT_STARTED') {
     return (
-      <li className="border-border-default rounded-100 flex items-center justify-between border p-300">
+      <li className="border-border-default rounded-100 flex items-center justify-between border bg-[#fff] p-300">
         <MissionCardContent
           title={mission.title}
           statusConfig={statusConfig}
@@ -137,7 +141,10 @@ export default function MissionCard({
               },
             }}
           />
-          <DeleteMissionModal missionId={mission.missionId} />
+          <DeleteMissionModal
+            missionId={mission.missionId}
+            groupStudyId={groupStudyId}
+          />
         </div>
       </li>
     );
@@ -147,7 +154,7 @@ export default function MissionCard({
   if (isLeader && mission.status === 'ENDED') {
     return (
       <li
-        className="border-border-default rounded-100 flex cursor-pointer items-center justify-between border p-300"
+        className="border-border-default rounded-100 flex cursor-pointer items-center justify-between border bg-[#fff] p-300"
         onClick={handleSelectMission}
       >
         <MissionCardContent
@@ -176,7 +183,7 @@ export default function MissionCard({
     return (
       <li
         className={cn(
-          'rounded-100 flex cursor-pointer items-center justify-between border p-300',
+          'rounded-100 flex cursor-pointer items-center justify-between border bg-[#fff] p-300',
           deadlineInfo?.isUrgent
             ? 'border-status-error'
             : 'border-border-default',
@@ -198,7 +205,7 @@ export default function MissionCard({
   return (
     <li
       className={cn(
-        'rounded-100 flex items-center justify-between border p-300',
+        'rounded-100 flex items-center justify-between border bg-[#fff] p-300',
         deadlineInfo?.isUrgent
           ? 'border-border-brand'
           : 'border-border-default',
diff --git a/src/components/contents/homework-detail-content.tsx b/src/components/contents/homework-detail-content.tsx
index 6fc26558..67df9c41 100644
--- a/src/components/contents/homework-detail-content.tsx
+++ b/src/components/contents/homework-detail-content.tsx
@@ -1,5 +1,6 @@
 'use client';
 
+import { useRouter, useSearchParams } from 'next/navigation';
 import { useState } from 'react';
 
 import type {
@@ -20,7 +21,7 @@ import {
   useDeletePeerReview,
   useUpdatePeerReview,
 } from '@/hooks/queries/peer-review-api';
-import { useIsLeader } from '@/providers/study-leader-context';
+import { useIsLeader } from '@/stores/useLeaderStore';
 import DeleteHomeworkModal from '../modals/delete-homework-modal';
 import EditHomeworkModal from '../modals/edit-homework-modal';
 
@@ -28,29 +29,22 @@ interface HomeworkDetailContentProps {
   groupStudyId: number;
   missionId: number;
   homeworkId: number;
-  onEdit?: () => void;
-  onDelete?: () => void;
 }
 
 export default function HomeworkDetailContent({
   homeworkId,
-  onEdit,
-  onDelete,
 }: HomeworkDetailContentProps) {
-  const isLeader = useIsLeader();
+  const router = useRouter();
+  const searchParams = useSearchParams();
   const currentUserId = useUserStore((state) => state.memberId);
+  const isLeader = useIsLeader(currentUserId);
   const { data: homework, isLoading: isHomeworkLoading } =
     useGetHomework(homeworkId);
-  const { mutate: deleteHomework, isPending: isDeleting } = useDeleteHomework();
 
-  const handleDelete = () => {
-    if (window.confirm('정말 삭제하시겠습니까?')) {
-      deleteHomework(homeworkId, {
-        onSuccess: () => {
-          onDelete?.();
-        },
-      });
-    }
+  const handleDeleteSuccess = () => {
+    const params = new URLSearchParams(searchParams.toString());
+    params.delete('homeworkId');
+    router.push(`?${params.toString()}`);
   };
 
   if (isHomeworkLoading || !homework) {
@@ -99,7 +93,10 @@ export default function HomeworkDetailContent({
                   attachmentLink: homework.homeworkContent.optionalContent.link,
                 }}
               />
-              <DeleteHomeworkModal homeworkId={homeworkId} />
+              <DeleteHomeworkModal
+                homeworkId={homeworkId}
+                onSuccess={handleDeleteSuccess}
+              />
             </div>
           )}
         </div>
diff --git a/src/components/contents/mission-detail-content.tsx b/src/components/contents/mission-detail-content.tsx
index 0a3c8cea..2009af0d 100644
--- a/src/components/contents/mission-detail-content.tsx
+++ b/src/components/contents/mission-detail-content.tsx
@@ -8,7 +8,7 @@ import Avatar from '@/components/ui/avatar';
 import Badge from '@/components/ui/badge';
 import Progress from '@/components/ui/progress';
 import { useGetMission } from '@/hooks/queries/mission-api';
-import { useIsLeader } from '@/providers/study-leader-context';
+import { useIsLeader } from '@/stores/useLeaderStore';
 import { useUserStore } from '@/stores/useUserStore';
 import MyHomeworkStatus from '../card/my-homework-status-card';
 
@@ -27,12 +27,10 @@ export default function MissionDetailContent({
   groupStudyId,
   missionId,
 }: MissionDetailContentProps) {
-  const isLeader = useIsLeader();
   const router = useRouter();
   const searchParams = useSearchParams();
   const memberId = useUserStore((state) => state.memberId);
-
-  console.log('memberId', memberId);
+  const isLeader = useIsLeader(memberId);
 
   const { data: mission, isLoading } = useGetMission(missionId);
 
@@ -58,8 +56,7 @@ export default function MissionDetailContent({
       (mission.maxHomeworkSubmissionCount ?? 1)) *
     100;
 
-  // TODO: 백엔드에서 MissionResponseDto에 status 필드 추가 후 교체 필요
-  const isMissionClosed = true;
+  const isMissionClosed = mission.status === 'ENDED';
 
   return (
     <div className="flex flex-col gap-400">
diff --git a/src/components/contents/payment-page-content.tsx b/src/components/contents/payment-page-content.tsx
index b7d1ddc6..15abf023 100644
--- a/src/components/contents/payment-page-content.tsx
+++ b/src/components/contents/payment-page-content.tsx
@@ -26,6 +26,8 @@ export default function PaymentPageContent({ id }: PaymentPageContentProps) {
 
   const data = result.data;
 
+  console.log(data);
+
   return (
     <div className="bg-background-alternative min-h-dvh">
       <div className="mx-auto max-w-[840px] pt-600">
@@ -37,6 +39,7 @@ export default function PaymentPageContent({ id }: PaymentPageContentProps) {
             <OrderSummary
               groupStudyTitle={data?.groupStudyTitle}
               amount={data.amount}
+              description={data.groupStudyDescription}
             />
           </section>
 
diff --git a/src/components/layout/sidebar/admin-sidebar.tsx b/src/components/layout/sidebar/admin-sidebar.tsx
index 2d2de52a..d41045fb 100644
--- a/src/components/layout/sidebar/admin-sidebar.tsx
+++ b/src/components/layout/sidebar/admin-sidebar.tsx
@@ -5,7 +5,7 @@ import { usePathname } from 'next/navigation';
 import UserAvatar from '@/components/ui/avatar';
 import TabMenu from '@/components/ui/tab-menu';
 import { useUserProfileQuery } from '@/entities/user/model/use-user-profile-query';
-import { useAuth } from '@/hooks/use-auth';
+import { useAuth } from '@/hooks/common/use-auth';
 import OutIcon from 'public/icons/out.svg';
 
 export default function AdminSideBar() {
diff --git a/src/components/lists/group-study-list.tsx b/src/components/lists/group-study-list.tsx
index 0a431b81..6f724cbb 100644
--- a/src/components/lists/group-study-list.tsx
+++ b/src/components/lists/group-study-list.tsx
@@ -4,7 +4,7 @@ import { sendGTMEvent } from '@next/third-parties/google';
 import Image from 'next/image';
 
 import { GroupStudyListItemDto } from '@/api/openapi';
-import { useAuth } from '@/hooks/use-auth';
+import { useAuth } from '@/hooks/common/use-auth';
 import { hashValue } from '@/utils/hash';
 
 import { GroupStudyData } from '../../features/study/group/api/group-study-types';
diff --git a/src/components/lists/study-member-list.tsx b/src/components/lists/study-member-list.tsx
index 5caff2ae..6e2f7249 100644
--- a/src/components/lists/study-member-list.tsx
+++ b/src/components/lists/study-member-list.tsx
@@ -4,9 +4,10 @@ import Image from 'next/image';
 import { useState } from 'react';
 import { GetGroupStudyMemberStatusResponseContent } from '@/api/openapi';
 import Pagination from '@/components/ui/pagination';
+import { useAuth } from '@/hooks/common/use-auth';
 import { useGetGroupStudyMembers } from '@/hooks/queries/group-study-member-api';
-import { useAuth } from '@/hooks/use-auth';
 import type { GroupStudyMember } from '../../features/study/group/api/group-study-types';
+
 import GroupStudyMemberItem from '../../features/study/group/ui/group-study-member-item';
 import KickedReasonModal from '../../features/study/group/ui/kicked-reason-modal';
 
@@ -45,7 +46,7 @@ export default function StudyMemberList({
   const totalPages = Math.ceil((data?.totalMemberCount || 0) / PAGE_SIZE) || 1;
 
   return (
-    <section className="flex flex-col gap-300">
+    <section className="mt-500 flex w-[1164px] flex-col gap-300">
       {/* 리더가 아닌 참가자에게 내 정보 상단에 노출 */}
       {!isLeader && (
         <SelfMemberInfo
diff --git a/src/components/modals/delete-homework-modal.tsx b/src/components/modals/delete-homework-modal.tsx
index 549a868c..be617de5 100644
--- a/src/components/modals/delete-homework-modal.tsx
+++ b/src/components/modals/delete-homework-modal.tsx
@@ -5,11 +5,13 @@ import { Modal } from '../ui/modal';
 
 interface DeleteHomeworkModalProps {
   homeworkId: number;
+  onSuccess?: () => void;
 }
 
 // 과제 삭제 모달
 export default function DeleteHomeworkModal({
   homeworkId,
+  onSuccess,
 }: DeleteHomeworkModalProps) {
   const [open, setOpen] = useState<boolean>(false);
 
@@ -20,6 +22,7 @@ export default function DeleteHomeworkModal({
       onSuccess: () => {
         alert('과제가 성공적으로 삭제되었습니다!');
         setOpen(false);
+        onSuccess?.();
       },
       onError: () => {
         alert('과제 삭제에 실패했습니다. 다시 시도해주세요.');
diff --git a/src/components/modals/delete-mission-modal.tsx b/src/components/modals/delete-mission-modal.tsx
index 2d88eb47..82a3ddbe 100644
--- a/src/components/modals/delete-mission-modal.tsx
+++ b/src/components/modals/delete-mission-modal.tsx
@@ -1,20 +1,41 @@
 import { useState } from 'react';
 
 import { MissionListResponse } from '@/api/openapi';
+import { useDeleteMission } from '@/hooks/queries/mission-api';
 import Button from '../ui/button';
 import { Modal } from '../ui/modal';
 
 interface DeleteMissionModalProps {
   missionId: MissionListResponse['missionId'];
+  groupStudyId: number;
+  onSuccess?: () => void;
 }
 
 // 미션 삭제 모달
 export default function DeleteMissionModal({
   missionId,
+  groupStudyId,
+  onSuccess,
 }: DeleteMissionModalProps) {
   const [open, setOpen] = useState<boolean>(false);
 
-  const handleDelete = () => {};
+  const { mutate: deleteMission } = useDeleteMission();
+
+  const handleDelete = () => {
+    deleteMission(
+      { missionId, groupStudyId },
+      {
+        onSuccess: () => {
+          alert('미션이 성공적으로 삭제되었습니다!');
+          setOpen(false);
+          onSuccess?.();
+        },
+        onError: () => {
+          alert('미션 삭제에 실패했습니다. 다시 시도해주세요.');
+        },
+      },
+    );
+  };
 
   return (
     <Modal.Root open={open} onOpenChange={setOpen}>
diff --git a/src/components/modals/edit-homework-modal.tsx b/src/components/modals/edit-homework-modal.tsx
index f4b2dbaa..9ad0a937 100644
--- a/src/components/modals/edit-homework-modal.tsx
+++ b/src/components/modals/edit-homework-modal.tsx
@@ -19,13 +19,15 @@ type EditHomeworkFormValues = z.infer<typeof EditHomeworkFormSchema>;
 
 interface EditHomeworkModalProps {
   defaultValue: EditHomeworkFormValues;
-  homeworkId: number; // todo api response 타입 적용
+  homeworkId: number;
+  onSuccess?: () => void;
 }
 
 // 과제 수정 모달
 export default function EditHomeworkModal({
   defaultValue,
   homeworkId,
+  onSuccess,
 }: EditHomeworkModalProps) {
   const [open, setOpen] = useState<boolean>(false);
 
@@ -57,6 +59,7 @@ export default function EditHomeworkModal({
             defaultValue={defaultValue}
             homeworkId={homeworkId}
             onClose={() => setOpen(false)}
+            onSuccess={onSuccess}
           />
         </Modal.Content>
       </Modal.Portal>
@@ -68,12 +71,14 @@ interface EditHomeworkFormProps {
   defaultValue: EditHomeworkFormValues;
   homeworkId: number;
   onClose: () => void;
+  onSuccess?: () => void;
 }
 
 function EditHomeworkForm({
   defaultValue,
   homeworkId,
   onClose,
+  onSuccess,
 }: EditHomeworkFormProps) {
   const methods = useForm<EditHomeworkFormValues>({
     resolver: zodResolver(EditHomeworkFormSchema),
@@ -101,6 +106,7 @@ function EditHomeworkForm({
         onSuccess: async () => {
           alert('과제가 성공적으로 수정되었습니다!');
           onClose();
+          onSuccess?.();
         },
         onError: () => {
           alert('과제 수정에 실패했습니다. 다시 시도해주세요.');
diff --git a/src/components/pages/group-study-detail-page.tsx b/src/components/pages/group-study-detail-page.tsx
index 05efdda2..c79b08f5 100644
--- a/src/components/pages/group-study-detail-page.tsx
+++ b/src/components/pages/group-study-detail-page.tsx
@@ -2,12 +2,12 @@
 
 import { sendGTMEvent } from '@next/third-parties/google';
 import { useRouter, useSearchParams } from 'next/navigation';
-import { useState } from 'react';
+import { useEffect, useState } from 'react';
 import MoreMenu from '@/components/ui/dropdown/more-menu';
 import Tabs from '@/components/ui/tabs';
 import { STUDY_DETAIL_TABS, StudyTabValue } from '@/config/constants';
 import { useGetGroupStudyMyStatus } from '@/hooks/queries/group-study-member-api';
-import { StudyLeaderProvider } from '@/providers/study-leader-context';
+import { useLeaderStore } from '@/stores/useLeaderStore';
 import { Leader } from '../../features/study/group/api/group-study-types';
 import ChannelSection from '../../features/study/group/channel/ui/channel-section';
 
@@ -35,6 +35,7 @@ export default function StudyDetailPage({
 }: StudyDetailPageProps) {
   const router = useRouter();
   const searchParams = useSearchParams();
+  const setLeaderInfo = useLeaderStore((state) => state.setLeaderInfo);
 
   const tabFromUrl = searchParams.get('tab') as StudyTabValue | null;
 
@@ -45,6 +46,13 @@ export default function StudyDetailPage({
 
   const isLeader = leaderId === memberId;
 
+  // 리더 정보를 Zustand store에 저장
+  useEffect(() => {
+    if (studyDetail?.basicInfo.leader) {
+      setLeaderInfo(studyDetail.basicInfo.leader as Leader);
+    }
+  }, [studyDetail?.basicInfo.leader, setLeaderInfo]);
+
   const [active, setActive] = useState<StudyTabValue>(tabFromUrl || 'intro');
   const [showModal, setShowModal] = useState<boolean>(false);
   const [action, setAction] = useState<ActionKey | null>(null);
@@ -129,104 +137,101 @@ export default function StudyDetailPage({
     return <div>로딩중...</div>;
   }
 
-  const leaderInfo = studyDetail.basicInfo.leader as Leader;
-
   return (
-    <StudyLeaderProvider leaderInfo={leaderInfo} memberId={memberId}>
-      <div className="m-auto flex w-full max-w-[1164px] flex-col gap-400 py-500">
-        <ConfirmDeleteModal
-          open={showModal}
-          onOpenChange={() => setShowModal(!showModal)}
-          title={ModalContent[action]?.title}
-          content={ModalContent[action]?.content}
-          confirmText={ModalContent[action]?.confirmText}
-          onConfirm={ModalContent[action]?.onConfirm}
-        />
-        <GroupStudyFormModal
-          open={showStudyFormModal}
-          mode="edit"
-          groupStudyId={groupStudyId}
-          onOpenChange={() => setShowStudyFormModal(!showStudyFormModal)}
-        />
-
-        <div className="flex w-full items-start justify-between">
-          <div className="flex w-full flex-col gap-150">
-            <p className="font-designer-28b text-[#181D27]">
-              {studyDetail?.detailInfo.title}
-            </p>
-            <p className="font-designer-18r text-[#252B37]">
-              {studyDetail?.detailInfo.summary}
-            </p>
-          </div>
-          {isLeader && (
-            <MoreMenu
-              options={[
-                {
-                  label: '스터디 수정하기',
-                  value: 'edit',
-                  onMenuClick: () => {
-                    setShowStudyFormModal(true);
-                  },
+    <div className="flex h-full w-full flex-col items-center">
+      <ConfirmDeleteModal
+        open={showModal}
+        onOpenChange={() => setShowModal(!showModal)}
+        title={ModalContent[action]?.title}
+        content={ModalContent[action]?.content}
+        confirmText={ModalContent[action]?.confirmText}
+        onConfirm={ModalContent[action]?.onConfirm}
+      />
+      <GroupStudyFormModal
+        open={showStudyFormModal}
+        mode="edit"
+        groupStudyId={groupStudyId}
+        onOpenChange={() => setShowStudyFormModal(!showStudyFormModal)}
+      />
+
+      <div className="my-500 flex w-[1164px] items-start justify-between">
+        <div className="flex w-full flex-col gap-150">
+          <p className="font-designer-28b text-[#181D27]">
+            {studyDetail?.detailInfo.title}
+          </p>
+          <p className="font-designer-18r text-[#252B37]">
+            {studyDetail?.detailInfo.summary}
+          </p>
+        </div>
+        {isLeader && (
+          <MoreMenu
+            options={[
+              {
+                label: '스터디 수정하기',
+                value: 'edit',
+                onMenuClick: () => {
+                  setShowStudyFormModal(true);
                 },
-                {
-                  label: '스터디 종료',
-                  value: 'end',
-                  onMenuClick: () => {
-                    setAction('end');
-                    setShowModal(true);
-                  },
+              },
+              {
+                label: '스터디 종료',
+                value: 'end',
+                onMenuClick: () => {
+                  setAction('end');
+                  setShowModal(true);
                 },
-                {
-                  label: '스터디 삭제',
-                  value: 'delete',
-                  onMenuClick: () => {
-                    setAction('delete');
-                    setShowModal(true);
-                  },
+              },
+              {
+                label: '스터디 삭제',
+                value: 'delete',
+                onMenuClick: () => {
+                  setAction('delete');
+                  setShowModal(true);
                 },
-              ]}
-              iconSize={35}
-            />
-          )}
-        </div>
-
-        {/** 탭리스트 */}
-        <Tabs
-          tabs={STUDY_DETAIL_TABS.filter(
-            (tab) => tab.value === 'intro' || isLeader || isMember,
-          )}
-          activeTab={active}
-          onChange={(value: StudyTabValue) => {
-            setActive(value);
-
-            // 탭 변경 시 URL 파라미터 초기화 및 탭 값 설정
-            router.replace(`?tab=${value}`);
-
-            sendGTMEvent({
-              event: 'group_study_tab_change',
-              group_study_id: String(groupStudyId),
-              tab: value,
-            });
-          }}
-        />
-        {active === 'intro' && <StudyInfoSection study={studyDetail} />}
-        {active === 'members' && (
-          <GroupStudyMemberList
-            groupStudyId={groupStudyId}
-            leaderId={studyDetail.basicInfo.leader.memberId}
-            myApplicationStatus={myApplicationStatus}
+              },
+            ]}
+            iconSize={35}
           />
         )}
+      </div>
 
-        {active === 'mission' && <MissionSection groupStudyId={groupStudyId} />}
-        {active === 'channel' && (
-          <ChannelSection
-            groupStudyId={groupStudyId}
-            memberId={memberId}
-            myApplicationStatus={myApplicationStatus}
-          />
+      {/** 탭리스트 */}
+      <Tabs
+        className="w-[1164px]"
+        tabs={STUDY_DETAIL_TABS.filter(
+          (tab) => tab.value === 'intro' || isLeader || isMember,
         )}
-      </div>
-    </StudyLeaderProvider>
+        activeTab={active}
+        onChange={(value: StudyTabValue) => {
+          setActive(value);
+
+          // 탭 변경 시 URL 파라미터 초기화 및 탭 값 설정
+          router.replace(`?tab=${value}`);
+
+          sendGTMEvent({
+            event: 'group_study_tab_change',
+            group_study_id: String(groupStudyId),
+            tab: value,
+          });
+        }}
+      />
+      {active === 'intro' && <StudyInfoSection study={studyDetail} />}
+      {active === 'members' && (
+        <GroupStudyMemberList
+          groupStudyId={groupStudyId}
+          leaderId={studyDetail.basicInfo.leader.memberId}
+          myApplicationStatus={myApplicationStatus}
+        />
+      )}
+
+      {active === 'mission' && <MissionSection groupStudyId={groupStudyId} />}
+      {active === 'channel' && (
+        <ChannelSection
+          groupStudyId={groupStudyId}
+          memberId={memberId}
+          myApplicationStatus={myApplicationStatus}
+        />
+      )}
+    </div>
   );
 }
diff --git a/src/components/pages/premium-study-detail-page.tsx b/src/components/pages/premium-study-detail-page.tsx
index dd2cec12..cac6719d 100644
--- a/src/components/pages/premium-study-detail-page.tsx
+++ b/src/components/pages/premium-study-detail-page.tsx
@@ -2,7 +2,7 @@
 
 import { sendGTMEvent } from '@next/third-parties/google';
 import { usePathname, useRouter, useSearchParams } from 'next/navigation';
-import { useState } from 'react';
+import { useEffect, useState } from 'react';
 import MoreMenu from '@/components/ui/dropdown/more-menu';
 import Tabs from '@/components/ui/tabs';
 import { STUDY_DETAIL_TABS, StudyTabValue } from '@/config/constants';
@@ -11,7 +11,7 @@ import {
   Leader,
 } from '@/features/study/group/api/group-study-types';
 import { useGetGroupStudyMyStatus } from '@/hooks/queries/group-study-member-api';
-import { StudyLeaderProvider } from '@/providers/study-leader-context';
+import { useLeaderStore } from '@/stores/useLeaderStore';
 import ChannelSection from '../../features/study/group/channel/ui/channel-section';
 import {
   useCompleteGroupStudyMutation,
@@ -38,6 +38,7 @@ export default function PremiumStudyDetailPage({
   const router = useRouter();
   const pathname = usePathname();
   const searchParams = useSearchParams();
+  const setLeaderInfo = useLeaderStore((state) => state.setLeaderInfo);
 
   const activeTab = (searchParams.get('tab') as StudyTabValue) || 'intro';
 
@@ -47,6 +48,13 @@ export default function PremiumStudyDetailPage({
   const leaderId = studyDetail?.basicInfo.leader.memberId;
 
   const isLeader = leaderId === memberId;
+
+  // 리더 정보를 Zustand store에 저장
+  useEffect(() => {
+    if (studyDetail?.basicInfo.leader) {
+      setLeaderInfo(studyDetail.basicInfo.leader as Leader);
+    }
+  }, [studyDetail?.basicInfo.leader, setLeaderInfo]);
   const [showModal, setShowModal] = useState<boolean>(false);
   const [action, setAction] = useState<ActionKey | null>(null);
   const [showStudyFormModal, setShowStudyFormModal] = useState<boolean>(false);
@@ -130,108 +138,105 @@ export default function PremiumStudyDetailPage({
     return <div>로딩중...</div>;
   }
 
-  const leaderInfo = studyDetail.basicInfo.leader as Leader;
-
   return (
-    <StudyLeaderProvider leaderInfo={leaderInfo} memberId={memberId}>
-      <div className="m-auto flex w-full max-w-[1164px] flex-col gap-400 py-500">
-        <ConfirmDeleteModal
-          open={showModal}
-          onOpenChange={() => setShowModal(!showModal)}
-          title={ModalContent[action]?.title}
-          content={ModalContent[action]?.content}
-          confirmText={ModalContent[action]?.confirmText}
-          onConfirm={ModalContent[action]?.onConfirm}
-        />
-        <GroupStudyFormModal
-          open={showStudyFormModal}
-          mode="edit"
-          groupStudyId={groupStudyId}
-          classification="PREMIUM_STUDY"
-          onOpenChange={() => setShowStudyFormModal(!showStudyFormModal)}
-        />
-
-        <div className="flex w-full items-start justify-between">
-          <div className="flex w-full flex-col gap-150">
-            <p className="font-designer-28b text-[#181D27]">
-              {studyDetail?.detailInfo.title}
-            </p>
-            <p className="font-designer-18r text-[#252B37]">
-              {studyDetail?.detailInfo.summary}
-            </p>
-          </div>
-          {isLeader && (
-            <MoreMenu
-              options={[
-                {
-                  label: '스터디 수정하기',
-                  value: 'edit',
-                  onMenuClick: () => {
-                    setShowStudyFormModal(true);
-                  },
+    <div className="flex h-full w-full flex-col items-center">
+      <ConfirmDeleteModal
+        open={showModal}
+        onOpenChange={() => setShowModal(!showModal)}
+        title={ModalContent[action]?.title}
+        content={ModalContent[action]?.content}
+        confirmText={ModalContent[action]?.confirmText}
+        onConfirm={ModalContent[action]?.onConfirm}
+      />
+      <GroupStudyFormModal
+        open={showStudyFormModal}
+        mode="edit"
+        groupStudyId={groupStudyId}
+        classification="PREMIUM_STUDY"
+        onOpenChange={() => setShowStudyFormModal(!showStudyFormModal)}
+      />
+
+      <div className="my-500 flex w-[1164px] items-start justify-between">
+        <div className="flex w-full flex-col gap-150">
+          <p className="font-designer-28b text-[#181D27]">
+            {studyDetail?.detailInfo.title}
+          </p>
+          <p className="font-designer-18r text-[#252B37]">
+            {studyDetail?.detailInfo.summary}
+          </p>
+        </div>
+        {isLeader && (
+          <MoreMenu
+            options={[
+              {
+                label: '스터디 수정하기',
+                value: 'edit',
+                onMenuClick: () => {
+                  setShowStudyFormModal(true);
                 },
-                {
-                  label: '스터디 종료',
-                  value: 'end',
-                  onMenuClick: () => {
-                    setAction('end');
-                    setShowModal(true);
-                  },
+              },
+              {
+                label: '스터디 종료',
+                value: 'end',
+                onMenuClick: () => {
+                  setAction('end');
+                  setShowModal(true);
                 },
-                {
-                  label: '스터디 삭제',
-                  value: 'delete',
-                  onMenuClick: () => {
-                    setAction('delete');
-                    setShowModal(true);
-                  },
+              },
+              {
+                label: '스터디 삭제',
+                value: 'delete',
+                onMenuClick: () => {
+                  setAction('delete');
+                  setShowModal(true);
                 },
-              ]}
-              iconSize={35}
-            />
-          )}
-        </div>
-
-        {/** 탭리스트 */}
-        <Tabs
-          tabs={STUDY_DETAIL_TABS.filter(
-            (tab) => tab.value === 'intro' || isLeader || isMember,
-          )}
-          activeTab={activeTab}
-          onChange={(value: StudyTabValue) => {
-            const params = new URLSearchParams(searchParams.toString());
-            params.set('tab', value);
-            router.push(`${pathname}?${params.toString()}`, { scroll: false });
-            sendGTMEvent({
-              event: 'premium_study_tab_change',
-              group_study_id: String(groupStudyId),
-              tab: value,
-            });
-          }}
-        />
-        {activeTab === 'intro' && (
-          <PremiumStudyInfoSection
-            study={studyDetail as GroupStudyFullResponse}
-          />
-        )}
-        {activeTab === 'members' && (
-          <GroupStudyMemberList
-            groupStudyId={groupStudyId}
-            leaderId={studyDetail.basicInfo.leader.memberId}
-            myApplicationStatus={myApplicationStatus}
-          />
-        )}
-        {activeTab === 'mission' && (
-          <MissionSection groupStudyId={groupStudyId} />
-        )}
-        {activeTab === 'channel' && (
-          <ChannelSection
-            groupStudyId={groupStudyId}
-            memberId={memberId}
-            myApplicationStatus={myApplicationStatus}
+              },
+            ]}
+            iconSize={35}
           />
         )}
       </div>
-    </StudyLeaderProvider>
+
+      {/** 탭리스트 */}
+      <Tabs
+        className="w-[1164px]"
+        tabs={STUDY_DETAIL_TABS.filter(
+          (tab) => tab.value === 'intro' || isLeader || isMember,
+        )}
+        activeTab={activeTab}
+        onChange={(value: StudyTabValue) => {
+          const params = new URLSearchParams(searchParams.toString());
+          params.set('tab', value);
+          router.push(`${pathname}?${params.toString()}`, { scroll: false });
+          sendGTMEvent({
+            event: 'premium_study_tab_change',
+            group_study_id: String(groupStudyId),
+            tab: value,
+          });
+        }}
+      />
+      {activeTab === 'intro' && (
+        <PremiumStudyInfoSection
+          study={studyDetail as GroupStudyFullResponse}
+        />
+      )}
+      {activeTab === 'members' && (
+        <GroupStudyMemberList
+          groupStudyId={groupStudyId}
+          leaderId={studyDetail.basicInfo.leader.memberId}
+          myApplicationStatus={myApplicationStatus}
+        />
+      )}
+      {activeTab === 'mission' && (
+        <MissionSection groupStudyId={groupStudyId} />
+      )}
+      {activeTab === 'channel' && (
+        <ChannelSection
+          groupStudyId={groupStudyId}
+          memberId={memberId}
+          myApplicationStatus={myApplicationStatus}
+        />
+      )}
+    </div>
   );
 }
diff --git a/src/components/payment/paymentActionClient.tsx b/src/components/payment/paymentActionClient.tsx
index 682a92c3..0d863c66 100644
--- a/src/components/payment/paymentActionClient.tsx
+++ b/src/components/payment/paymentActionClient.tsx
@@ -29,7 +29,7 @@ export default function PaymentCheckoutPage({ study }: Props) {
 
   const [paymentMethod, setPaymentMethod] = useState<PaymentMethod>('CARD');
 
-  const canPay = isAgreed && !!paymentMethod && !!payment && !isLoading;
+  const canPay = isAgreed && !!paymentMethod && !isLoading;
 
   const toggleTerm = () => {
     setIsAgreed((prev) => !prev);
diff --git a/src/components/premium/premium-study-list.tsx b/src/components/premium/premium-study-list.tsx
index f07c4345..5ccb546b 100644
--- a/src/components/premium/premium-study-list.tsx
+++ b/src/components/premium/premium-study-list.tsx
@@ -5,7 +5,7 @@ import Image from 'next/image';
 
 import { GroupStudyListItemDto } from '@/api/openapi';
 import { GroupStudyData } from '@/features/study/group/api/group-study-types';
-import { useAuth } from '@/hooks/use-auth';
+import { useAuth } from '@/hooks/common/use-auth';
 import { hashValue } from '@/utils/hash';
 
 import StudyCard from '../card/study-card';
diff --git a/src/components/section/group-study-info-section.tsx b/src/components/section/group-study-info-section.tsx
index d6ef1046..3356c01c 100644
--- a/src/components/section/group-study-info-section.tsx
+++ b/src/components/section/group-study-info-section.tsx
@@ -10,8 +10,9 @@ import Button from '@/components/ui/button';
 import { getSincerityPresetByLevelName } from '@/config/sincerity-temp-presets';
 import UserProfileModal from '@/entities/user/ui/user-profile-modal';
 import { useApplicantsByStatusQuery } from '@/features/study/group/application/model/use-applicant-qeury';
-import { useAuth } from '@/hooks/use-auth';
-import { useIsLeader } from '@/providers/study-leader-context';
+import { useAuth } from '@/hooks/common/use-auth';
+import { useIsLeader } from '@/stores/useLeaderStore';
+import { useUserStore } from '@/stores/useUserStore';
 import { hashValue } from '@/utils/hash';
 
 import SummaryStudyInfo from '../summary/study-info-summary';
@@ -23,10 +24,11 @@ interface StudyInfoSectionProps {
 export default function StudyInfoSection({
   study: studyDetail,
 }: StudyInfoSectionProps) {
-  const isLeader = useIsLeader();
   const router = useRouter();
   const params = useParams();
   const { data: authData } = useAuth();
+  const memberId = useUserStore((state) => state.memberId);
+  const isLeader = useIsLeader(memberId);
 
   const groupStudyId = Number(params.id);
 
@@ -42,7 +44,7 @@ export default function StudyInfoSection({
   return (
     // todo: 스터디 공지 모달 추가
     // <GroupStudyNoticeModal groupStudyId={groupStudyId} />
-    <div className="flex w-full gap-600">
+    <div className="m-auto mt-500 flex w-[1164px] gap-600">
       <div className="flex flex-1 flex-col gap-500">
         <div className="relative h-[430px] w-full">
           <Image
diff --git a/src/components/section/mission-section.tsx b/src/components/section/mission-section.tsx
index be13e6cc..49f10ab9 100644
--- a/src/components/section/mission-section.tsx
+++ b/src/components/section/mission-section.tsx
@@ -4,11 +4,12 @@ import { ChevronLeft } from 'lucide-react';
 import { useRouter, useSearchParams } from 'next/navigation';
 import { useState } from 'react';
 import { useGetMissions } from '@/hooks/queries/mission-api';
-import { useIsLeader } from '@/providers/study-leader-context';
+import { useIsLeader } from '@/stores/useLeaderStore';
+import { useUserStore } from '@/stores/useUserStore';
 import MissionCard from '../card/mission-card';
-import CreateMissionModal from '../modals/create-mission-modal';
 import HomeworkDetailContent from '../contents/homework-detail-content';
 import MissionDetailContent from '../contents/mission-detail-content';
+import CreateMissionModal from '../modals/create-mission-modal';
 import { cn } from '../ui/(shadcn)/lib/utils';
 
 type FilterType = 'all' | 'inProgress' | 'completed';
@@ -18,9 +19,10 @@ interface MissionSectionProps {
 }
 
 export default function MissionSection({ groupStudyId }: MissionSectionProps) {
-  const isLeader = useIsLeader();
   const router = useRouter();
   const searchParams = useSearchParams();
+  const memberId = useUserStore((state) => state.memberId);
+  const isLeader = useIsLeader(memberId);
   const [filter, setFilter] = useState<FilterType>('all');
 
   const missionId = searchParams.get('missionId');
@@ -154,37 +156,40 @@ export default function MissionSection({ groupStudyId }: MissionSectionProps) {
 
   // 미션 목록 (기본)
   return (
-    <section className="flex flex-col gap-300">
-      <div className="flex items-center justify-between">
-        <span className="font-designer-20b text-text-default">미션 목록</span>
-        {isLeader && <CreateMissionModal groupStudyId={groupStudyId} />}
-      </div>
+    <section className="bg-background-alternative flex h-full w-full flex-col gap-300">
+      <div className="m-auto mt-500 w-[1164px]">
+        <div className="flex items-center justify-between">
+          <span className="font-designer-20b text-text-default">미션 목록</span>
+          {isLeader && <CreateMissionModal groupStudyId={groupStudyId} />}
+        </div>
 
-      <MissionFilterTabs
-        filter={filter}
-        onFilterChange={setFilter}
-        totalCount={missionList?.length || 0}
-        inProgressCount={inProgressMissions.length}
-        completedCount={completedMissions.length}
-      />
-
-      {hasMissions ? (
-        <ul className="flex flex-col gap-200">
-          {filteredMissions.map((mission) => (
-            <MissionCard
-              key={mission.missionId}
-              mission={mission}
-              onSelectMission={handleSelectMission}
-              showDeadline={
-                mission.status === 'IN_PROGRESS' ||
-                mission.status === 'NOT_STARTED'
-              }
-            />
-          ))}
-        </ul>
-      ) : (
-        <EmptyMissionState />
-      )}
+        <MissionFilterTabs
+          filter={filter}
+          onFilterChange={setFilter}
+          totalCount={missionList?.length || 0}
+          inProgressCount={inProgressMissions.length}
+          completedCount={completedMissions.length}
+        />
+
+        {hasMissions ? (
+          <ul className="flex flex-col gap-200">
+            {filteredMissions.map((mission) => (
+              <MissionCard
+                key={mission.missionId}
+                mission={mission}
+                groupStudyId={groupStudyId}
+                onSelectMission={handleSelectMission}
+                showDeadline={
+                  mission.status === 'IN_PROGRESS' ||
+                  mission.status === 'NOT_STARTED'
+                }
+              />
+            ))}
+          </ul>
+        ) : (
+          <EmptyMissionState />
+        )}
+      </div>
     </section>
   );
 }
@@ -209,7 +214,7 @@ function MissionFilterTabs({
   ];
 
   return (
-    <div className="flex gap-100">
+    <div className="mt-400 mb-200 flex gap-100">
       {tabs.map((tab) => (
         <button
           key={tab.key}
diff --git a/src/components/section/premium-study-info-section.tsx b/src/components/section/premium-study-info-section.tsx
index c225d7b6..022edfba 100644
--- a/src/components/section/premium-study-info-section.tsx
+++ b/src/components/section/premium-study-info-section.tsx
@@ -8,8 +8,9 @@ import UserAvatar from '@/components/ui/avatar';
 import Button from '@/components/ui/button';
 import { getSincerityPresetByLevelName } from '@/config/sincerity-temp-presets';
 import UserProfileModal from '@/entities/user/ui/user-profile-modal';
-import { useAuth } from '@/hooks/use-auth';
-import { useIsLeader } from '@/providers/study-leader-context';
+import { useAuth } from '@/hooks/common/use-auth';
+import { useIsLeader } from '@/stores/useLeaderStore';
+import { useUserStore } from '@/stores/useUserStore';
 import { hashValue } from '@/utils/hash';
 
 import { GroupStudyFullResponse } from '../../features/study/group/api/group-study-types';
@@ -30,10 +31,11 @@ interface PremiumStudyInfoSectionProps {
 export default function PremiumStudyInfoSection({
   study: studyDetail,
 }: PremiumStudyInfoSectionProps) {
-  const isLeader = useIsLeader();
   const router = useRouter();
   const params = useParams();
   const { data: authData } = useAuth();
+  const memberId = useUserStore((state) => state.memberId);
+  const isLeader = useIsLeader(memberId);
 
   const groupStudyId = Number(params.id);
 
@@ -45,7 +47,7 @@ export default function PremiumStudyInfoSection({
   const applicantsList = getApplicantsList(approvedApplicants?.pages);
 
   return (
-    <div className="flex w-full gap-600">
+    <div className="mt-500 flex w-[1164px] gap-600">
       <div className="flex flex-1 flex-col gap-500">
         <div className="relative h-[430px] w-full">
           <Image
diff --git a/src/components/summary/order-summary.tsx b/src/components/summary/order-summary.tsx
index d1126f38..f55100a9 100644
--- a/src/components/summary/order-summary.tsx
+++ b/src/components/summary/order-summary.tsx
@@ -1,9 +1,14 @@
 interface Props {
   groupStudyTitle: string;
+  description: string;
   amount: number;
 }
 
-export default function OrderSummary({ groupStudyTitle, amount }: Props) {
+export default function OrderSummary({
+  groupStudyTitle,
+  amount,
+  description,
+}: Props) {
   return (
     <div className="flex flex-col gap-300">
       <div className="flex items-center gap-250">
@@ -11,8 +16,9 @@ export default function OrderSummary({ groupStudyTitle, amount }: Props) {
         <div className="flex flex-1 flex-row items-end justify-between">
           <div className="space-y-1">
             <p className="font-designer-16m">{groupStudyTitle}</p>
+            <p className="font-designer-14r text-text-subtle">{description}</p>
           </div>
-          <p className="font-designer-14r text-text-subtle">
+          <p className="font-designer-15r text-text-subtle">
             {amount.toLocaleString()}원
           </p>
         </div>
diff --git a/src/components/ui/tabs/index.tsx b/src/components/ui/tabs/index.tsx
index 201d549d..9c9bb1f4 100644
--- a/src/components/ui/tabs/index.tsx
+++ b/src/components/ui/tabs/index.tsx
@@ -26,7 +26,7 @@ export default function Tabs({
   return (
     <div
       className={cn(
-        'border-border-subtle flex w-full cursor-pointer gap-200 border-b-[1px]',
+        'border-border-subtle flex w-full cursor-pointer gap-200 border-b',
         className,
       )}
     >
diff --git a/src/config/sincerity-temp-presets.tsx b/src/config/sincerity-temp-presets.tsx
index b1d40334..9fb488b0 100644
--- a/src/config/sincerity-temp-presets.tsx
+++ b/src/config/sincerity-temp-presets.tsx
@@ -1,7 +1,7 @@
-import TempType1 from '@/shared/icons/temp_1.svg';
-import TempType2 from '@/shared/icons/temp_2.svg';
-import TempType3 from '@/shared/icons/temp_3.svg';
-import TempType4 from '@/shared/icons/temp_4.svg';
+import TempType1 from 'public/icons/temp_1.svg';
+import TempType2 from 'public/icons/temp_2.svg';
+import TempType3 from 'public/icons/temp_3.svg';
+import TempType4 from 'public/icons/temp_4.svg';
 
 export type SincerityLabel = '1단계' | '2단계' | '3단계' | '4단계';
 
diff --git a/src/features/auth/ui/header-user-dropdown.tsx b/src/features/auth/ui/header-user-dropdown.tsx
index 0d4045af..e6f6fc0a 100644
--- a/src/features/auth/ui/header-user-dropdown.tsx
+++ b/src/features/auth/ui/header-user-dropdown.tsx
@@ -8,7 +8,7 @@ import {
   DropdownMenuTrigger,
 } from '@/components/ui/(shadcn)/ui/dropdown-menu';
 import UserAvatar from '@/components/ui/avatar';
-import { useAuth } from '@/hooks/use-auth';
+import { useAuth } from '@/hooks/common/use-auth';
 import { useLogoutMutation } from '../model/use-auth-mutation';
 
 export default function HeaderUserDropdown({ userImg }: { userImg: string }) {
diff --git a/src/features/my-page/ui/applicant-page.tsx b/src/features/my-page/ui/applicant-page.tsx
index 06adf71e..f3213d99 100644
--- a/src/features/my-page/ui/applicant-page.tsx
+++ b/src/features/my-page/ui/applicant-page.tsx
@@ -45,7 +45,7 @@ export default function ApplicantPage(props: ApplicantListProps) {
   };
 
   return (
-    <div className="w-720px flex flex-col gap-300">
+    <div className="m-auto flex w-[720px] flex-col gap-300">
       <div className="font-designer-20b flex items-center">
         <Image
           src="/icons/arrow-left-line.svg"
diff --git a/src/features/study/group/channel/ui/channel-section.tsx b/src/features/study/group/channel/ui/channel-section.tsx
index 0c974aa6..25be60e6 100644
--- a/src/features/study/group/channel/ui/channel-section.tsx
+++ b/src/features/study/group/channel/ui/channel-section.tsx
@@ -25,7 +25,7 @@ export default function ChannelSection({
 
   // 등록되지 않은 경우
   if (!data?.isRegistered) {
-    return memberId === leader.memberId ? (
+    return memberId === leader?.memberId ? (
       <CreatePost groupStudyId={groupStudyId} />
     ) : (
       <PostNotFound />
@@ -34,7 +34,7 @@ export default function ChannelSection({
 
   // 등록된 경우
   return (
-    <>
+    <div className="mt-500 w-[1164px]">
       <div className="flex flex-col gap-500">
         <Post data={data} />
         <Comments groupStudyId={groupStudyId} />
@@ -43,6 +43,6 @@ export default function ChannelSection({
       {myApplicationStatus?.status === 'KICKED' && (
         <KickedReasonModal reason={myApplicationStatus.reason} />
       )}
-    </>
+    </div>
   );
 }
diff --git a/src/features/study/group/channel/ui/comment.tsx b/src/features/study/group/channel/ui/comment.tsx
index c4999188..6c787f81 100644
--- a/src/features/study/group/channel/ui/comment.tsx
+++ b/src/features/study/group/channel/ui/comment.tsx
@@ -5,7 +5,7 @@ import UserAvatar from '@/components/ui/avatar';
 import MoreMenu from '@/components/ui/dropdown/more-menu';
 import UserProfileModal from '@/entities/user/ui/user-profile-modal';
 
-import { useLeaderInfo } from '@/providers/study-leader-context';
+import { useLeaderInfo } from '@/stores/useLeaderStore';
 import { useUserStore } from '@/stores/useUserStore';
 import CommentInput from './comment-input';
 import { ResizedImage } from '../../api/group-study-types';
diff --git a/src/features/study/group/channel/ui/create-post.tsx b/src/features/study/group/channel/ui/create-post.tsx
index 0ea6acec..363cac8c 100644
--- a/src/features/study/group/channel/ui/create-post.tsx
+++ b/src/features/study/group/channel/ui/create-post.tsx
@@ -7,7 +7,7 @@ interface CreatePostProps {
 
 export default function CreatePost({ groupStudyId }: CreatePostProps) {
   return (
-    <div className="bg-background-alternative rounded-100 flex h-[640px] w-full items-center justify-center border-2 border-dashed border-[#D5D7DA]">
+    <div className="bg-background-alternative rounded-100 mt-500 flex h-[640px] w-[1164px] items-center justify-center border-2 border-dashed border-[#D5D7DA]">
       <div className="flex flex-col gap-200 text-center">
         <p className="font-designer-20b">스터디에 대한 공지를 남겨주세요</p>
         <div className="font-designer-14r">
diff --git a/src/features/study/group/channel/ui/post-not-found.tsx b/src/features/study/group/channel/ui/post-not-found.tsx
index 752df4a6..0de7ac61 100644
--- a/src/features/study/group/channel/ui/post-not-found.tsx
+++ b/src/features/study/group/channel/ui/post-not-found.tsx
@@ -3,7 +3,7 @@ import React from 'react';
 
 export default function PostNotFound() {
   return (
-    <div className="bg-background-alternative flex h-[640px] w-full">
+    <div className="bg-background-alternative flex h-[640px]">
       <div className="m-auto flex flex-col items-center">
         <Image
           src="/images/post_not_found.png"
diff --git a/src/features/study/group/channel/ui/post.tsx b/src/features/study/group/channel/ui/post.tsx
index 50cdd5f4..55a2d053 100644
--- a/src/features/study/group/channel/ui/post.tsx
+++ b/src/features/study/group/channel/ui/post.tsx
@@ -16,6 +16,8 @@ interface PostProps {
 export default function Post({ data }: PostProps) {
   const leader = useLeaderStore((state) => state.leaderInfo);
 
+  if (!leader) return null;
+
   return (
     <div className="flex flex-col border-b border-[#D5D7DA]">
       <div className="mb-500 flex flex-col gap-250">
diff --git a/src/features/study/group/ui/group-study-member-item.tsx b/src/features/study/group/ui/group-study-member-item.tsx
index b0efb89a..73bbd527 100644
--- a/src/features/study/group/ui/group-study-member-item.tsx
+++ b/src/features/study/group/ui/group-study-member-item.tsx
@@ -9,7 +9,7 @@ import UserAvatar from '@/components/ui/avatar';
 
 import Button from '@/components/ui/button';
 import UserProfileModal from '@/entities/user/ui/user-profile-modal';
-import { useAuth } from '@/hooks/use-auth';
+import { useAuth } from '@/hooks/common/use-auth';
 import BronzeRankIcon from 'public/icons/bronze-rank.svg';
 import CaretDownIcon from 'public/icons/caret-down.svg';
 import CaretUpIcon from 'public/icons/caret-up.svg';
diff --git a/src/features/study/group/ui/step/step1-group.tsx b/src/features/study/group/ui/step/step1-group.tsx
index 74a3c878..d76a3763 100644
--- a/src/features/study/group/ui/step/step1-group.tsx
+++ b/src/features/study/group/ui/step/step1-group.tsx
@@ -250,6 +250,7 @@ export default function Step1OpenGroupStudy() {
             render={({ field }) => (
               <BaseInput
                 type="number"
+                step={10000}
                 min={10000}
                 placeholder="10,000"
                 value={field.value}
diff --git a/src/features/study/participation/ui/reservation-list.tsx b/src/features/study/participation/ui/reservation-list.tsx
index 7d5c60da..8b610e40 100644
--- a/src/features/study/participation/ui/reservation-list.tsx
+++ b/src/features/study/participation/ui/reservation-list.tsx
@@ -9,7 +9,7 @@ import {
 import ProfileDefault from '@/entities/user/ui/icon/profile-default.svg';
 import ReservationCard from '@/features/study/participation/ui/reservation-user-card';
 import StartStudyModal from '@/features/study/participation/ui/start-study-modal';
-import { useAuth } from '@/hooks/use-auth';
+import { useAuth } from '@/hooks/common/use-auth';
 import { useInfiniteReservation } from '../model/use-participation-query';
 
 interface ReservationListProps {
diff --git a/src/features/study/schedule/ui/today-study-card.tsx b/src/features/study/schedule/ui/today-study-card.tsx
index 72a8c9c4..e33db149 100644
--- a/src/features/study/schedule/ui/today-study-card.tsx
+++ b/src/features/study/schedule/ui/today-study-card.tsx
@@ -6,7 +6,7 @@ import UserAvatar from '@/components/ui/avatar';
 import Badge from '@/components/ui/badge';
 import UserPhoneNumberCopyModal from '@/entities/user/ui/user-phone-number-copy-modal';
 import UserProfileModal from '@/entities/user/ui/user-profile-modal';
-import { useAuth } from '@/hooks/use-auth';
+import { useAuth } from '@/hooks/common/use-auth';
 import { DailyStudyDetail } from '../../interview/api/interview-types';
 import { useDailyStudyDetailQuery } from '../../interview/model/use-interview-query';
 import { getStatusBadge } from '../../interview/ui/status-badge-map';
diff --git a/src/hooks/use-auth.ts b/src/hooks/common/use-auth.ts
similarity index 100%
rename from src/hooks/use-auth.ts
rename to src/hooks/common/use-auth.ts
diff --git a/src/hooks/queries/group-study-homework-api.ts b/src/hooks/queries/group-study-homework-api.ts
index 7b5d7361..f801b281 100644
--- a/src/hooks/queries/group-study-homework-api.ts
+++ b/src/hooks/queries/group-study-homework-api.ts
@@ -64,10 +64,13 @@ export const useEditHomework = () => {
 
       return data.content;
     },
-    onSuccess: async () => {
+    onSuccess: async (_, variables) => {
       await queryClient.invalidateQueries({
         queryKey: ['homeworks'],
       });
+      await queryClient.invalidateQueries({
+        queryKey: ['homework', variables.homeworkId],
+      });
     },
   });
 };
diff --git a/src/hooks/queries/group-study-member-api.ts b/src/hooks/queries/group-study-member-api.ts
index fb881eac..7f3ee3c5 100644
--- a/src/hooks/queries/group-study-member-api.ts
+++ b/src/hooks/queries/group-study-member-api.ts
@@ -7,7 +7,7 @@ import type {
 } from '@/api/openapi/models';
 // TEMPORARY: Keep until OpenAPI types fixed
 import type { GroupStudyMembersResponse } from '@/features/study/group/api/group-study-types';
-import { useAuth } from '../use-auth';
+import { useAuth } from '../common/use-auth';
 
 const groupStudyMemberApi = createApiInstance(GroupStudyMemberApi);
 
diff --git a/src/hooks/queries/mission-api.ts b/src/hooks/queries/mission-api.ts
index ffb89241..b9111b21 100644
--- a/src/hooks/queries/mission-api.ts
+++ b/src/hooks/queries/mission-api.ts
@@ -85,10 +85,35 @@ export const useUpdateMission = () => {
 
       return data.content;
     },
-    onSuccess: async () => {
+    onSuccess: async (_, variables) => {
       await queryClient.invalidateQueries({
         queryKey: ['missions'],
       });
+      await queryClient.invalidateQueries({
+        queryKey: ['mission', variables.missionId],
+      });
+    },
+  });
+};
+
+export const useDeleteMission = () => {
+  const queryClient = useQueryClient();
+
+  return useMutation({
+    mutationFn: async ({
+      missionId,
+    }: {
+      missionId: number;
+      groupStudyId: number;
+    }) => {
+      const { data } = await missionApi.deleteMission(missionId);
+
+      return data.content;
+    },
+    onSuccess: async (_, variables) => {
+      await queryClient.invalidateQueries({
+        queryKey: ['missions', variables.groupStudyId],
+      });
     },
   });
 };
diff --git a/src/hooks/queries/notification-api.ts b/src/hooks/queries/notification-api.ts
index ef3ba516..07cd6b5a 100644
--- a/src/hooks/queries/notification-api.ts
+++ b/src/hooks/queries/notification-api.ts
@@ -2,7 +2,7 @@ import { useMutation, useQuery, useQueryClient } from '@tanstack/react-query';
 import { createApiInstance } from '@/api/client/open-api-instance';
 import { NotificationApi } from '@/api/openapi';
 import type { GetMemberNotificationsTopicTypeEnum } from '@/api/openapi/api/notification-api';
-import { useAuth } from '../use-auth';
+import { useAuth } from '../common/use-auth';
 
 const notificationApi = createApiInstance(NotificationApi);
 
diff --git a/src/providers/index.tsx b/src/providers/index.tsx
index a21b6978..89cf3cfd 100644
--- a/src/providers/index.tsx
+++ b/src/providers/index.tsx
@@ -2,7 +2,7 @@
 
 import { ReactQueryDevtools } from '@tanstack/react-query-devtools';
 import { useEffect } from 'react';
-import { useAuth } from '@/hooks/use-auth';
+import { useAuth } from '@/hooks/common/use-auth';
 import QueryProvider from '@/providers/query-provider';
 import { useUserStore } from '@/stores/useUserStore';
 
diff --git a/src/providers/study-leader-context.tsx b/src/providers/study-leader-context.tsx
deleted file mode 100644
index 9b6526b0..00000000
--- a/src/providers/study-leader-context.tsx
+++ /dev/null
@@ -1,63 +0,0 @@
-'use client';
-
-import { createContext, useContext, useMemo, ReactNode } from 'react';
-import { Leader } from '@/features/study/group/api/group-study-types';
-
-interface StudyLeaderContextValue {
-  leaderInfo: Leader | null;
-  leaderId: number | undefined;
-  isLeader: boolean;
-}
-
-const StudyLeaderContext = createContext<StudyLeaderContextValue | null>(null);
-
-interface StudyLeaderProviderProps {
-  children: ReactNode;
-  leaderInfo: Leader | null;
-  memberId?: number;
-}
-
-export function StudyLeaderProvider({
-  children,
-  leaderInfo,
-  memberId,
-}: StudyLeaderProviderProps) {
-  const value = useMemo(() => {
-    const leaderId = leaderInfo?.memberId;
-    const isLeader = leaderId !== undefined && leaderId === memberId;
-
-    return {
-      leaderInfo,
-      leaderId,
-      isLeader,
-    };
-  }, [leaderInfo, memberId]);
-
-  return (
-    <StudyLeaderContext.Provider value={value}>
-      {children}
-    </StudyLeaderContext.Provider>
-  );
-}
-
-export function useStudyLeader(): StudyLeaderContextValue {
-  const context = useContext(StudyLeaderContext);
-
-  if (context === null) {
-    throw new Error('useStudyLeader must be used within a StudyLeaderProvider');
-  }
-
-  return context;
-}
-
-export function useIsLeader(): boolean {
-  const { isLeader } = useStudyLeader();
-
-  return isLeader;
-}
-
-export function useLeaderInfo(): Leader | null {
-  const { leaderInfo } = useStudyLeader();
-
-  return leaderInfo;
-}
diff --git a/src/shared/icons/plus.svg b/src/shared/icons/plus.svg
deleted file mode 100644
index 897e8420..00000000
--- a/src/shared/icons/plus.svg
+++ /dev/null
@@ -1,3 +0,0 @@
-<svg width="24" height="24" viewBox="0 0 24 24" fill="none" xmlns="http://www.w3.org/2000/svg">
-<path d="M19 13H13V19H11V13H5V11H11V5H13V11H19V13Z" fill="white"/>
-</svg>
diff --git a/src/stores/useLeaderStore.ts b/src/stores/useLeaderStore.ts
index 54a9d434..39399bf3 100644
--- a/src/stores/useLeaderStore.ts
+++ b/src/stores/useLeaderStore.ts
@@ -2,11 +2,25 @@ import { create } from 'zustand';
 import { Leader } from '@/features/study/group/api/group-study-types';
 
 interface LeaderStore {
-  leaderInfo: Leader; // 전역으로 들고 있을 값
-  setLeaderInfo: (v: Leader) => void; // 값을 세팅하는 액션
+  leaderInfo: Leader | null;
+  setLeaderInfo: (v: Leader | null) => void;
+  reset: () => void;
 }
 
 export const useLeaderStore = create<LeaderStore>((set) => ({
   leaderInfo: null,
   setLeaderInfo: (v) => set({ leaderInfo: v }),
+  reset: () => set({ leaderInfo: null }),
 }));
+
+// Context에서 제공하던 훅들을 Zustand 기반으로 구현
+export function useLeaderInfo(): Leader | null {
+  return useLeaderStore((state) => state.leaderInfo);
+}
+
+export function useIsLeader(memberId: number | null): boolean {
+  const leaderInfo = useLeaderStore((state) => state.leaderInfo);
+  if (!leaderInfo || !memberId) return false;
+
+  return leaderInfo.memberId === memberId;
+}
diff --git a/src/widgets/my-page/sidebar.tsx b/src/widgets/my-page/sidebar.tsx
index 8e509cb3..69a014ee 100644
--- a/src/widgets/my-page/sidebar.tsx
+++ b/src/widgets/my-page/sidebar.tsx
@@ -4,7 +4,7 @@ import { usePathname, useRouter } from 'next/navigation';
 import { cn } from '@/components/ui/(shadcn)/lib/utils';
 import { useUserProfileQuery } from '@/entities/user/model/use-user-profile-query';
 import { useLogoutMutation } from '@/features/auth/model/use-auth-mutation';
-import { useAuth } from '@/hooks/use-auth';
+import { useAuth } from '@/hooks/common/use-auth';
 
 export default function Sidebar() {
   const router = useRouter();