diff --git a/.idea/workspace.xml b/.idea/workspace.xml
index 604b182..1bc1f9c 100644
--- a/.idea/workspace.xml
+++ b/.idea/workspace.xml
@@ -6,7 +6,9 @@
   <component name="ChangeListManager">
     <list default="true" id="aa057fb3-95e3-4ca5-9656-3792bd70e880" name="변경" comment="">
       <change beforePath="$PROJECT_DIR$/.idea/workspace.xml" beforeDir="false" afterPath="$PROJECT_DIR$/.idea/workspace.xml" afterDir="false" />
-      <change beforePath="$PROJECT_DIR$/src/services/task.service.js" beforeDir="false" afterPath="$PROJECT_DIR$/src/services/task.service.js" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/src/controllers/category.controller.js" beforeDir="false" afterPath="$PROJECT_DIR$/src/controllers/category.controller.js" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/src/controllers/task.controller.js" beforeDir="false" afterPath="$PROJECT_DIR$/src/controllers/task.controller.js" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/src/dtos/task.dto.js" beforeDir="false" afterPath="$PROJECT_DIR$/src/dtos/task.dto.js" afterDir="false" />
     </list>
     <option name="SHOW_DIALOG" value="false" />
     <option name="HIGHLIGHT_CONFLICTS" value="true" />
diff --git a/src/controllers/category.controller.js b/src/controllers/category.controller.js
index bfdab65..32493c2 100644
--- a/src/controllers/category.controller.js
+++ b/src/controllers/category.controller.js
@@ -5,7 +5,12 @@ import {createCategoryService,
         createTaskCategory,
         createTaskCategoryBulk,
         createCategoryBulk
-} from '../services/category.service.js'
+} from '../services/category.service.js';
+import { transformCategoryListResponse,
+        transformCategoryResponse,
+        transformTaskResponse,
+        transformTaskListResponse
+ } from '../dtos/task.dto.js';
 import { createTaskBulkDto, createTaskDto } from '../dtos/task.dto.js';
 import { deleteCategoryRepository } from '../repositories/category.repository.js';
 import { DuplicateCategoryError, AuthError } from '../errors.js';
@@ -47,10 +52,12 @@ export const handleCreateCategory = async (req, res, next) => {
             throw new AuthError;
         }
 
+        // 생성된 카테고리 반환 
+        const createdCategory = await createCategoryService({ userId, name }); // 서비스 호출
 
-        const createdTaskCategory = await createCategoryService({ userId, name }); // 서비스 호출
-
-        res.success(createdTaskCategory); // 성공 응답
+        res.success(
+            transformCategoryResponse(createdCategory)
+        ); // 성공 응답
     } catch (error) {
         next(error); // 전역 오류 처리 미들웨어로 전달
     }
@@ -97,7 +104,7 @@ export const handleCreateCategoryBulk = async (req, res, next) => {
          
         const createdCategories = await createCategoryBulk({ userId, names }); // 서비스 호출
         // 성공 응답
-        res.success(createdCategories); 
+        res.success(transformCategoryListResponse(createdCategories)); 
    } catch (error) {
        next(error); 
    }
@@ -147,8 +154,8 @@ export const handleUpdateCategory = async (req, res, next) => {
             });
         }
 
-        const updatedTaskCategory = await updateCategoryService(task_category_id, name, userId); // 서비스 호출
-        res.success(updatedTaskCategory); // 성공 응답
+        const updatedCategory = await updateCategoryService(task_category_id, name, userId); // 서비스 호출
+        res.success(transformCategoryResponse(updatedCategory)); // 성공 응답
     } catch (error) {
         next(error); // 전역 오류 처리 미들웨어로 전달
     }
@@ -214,7 +221,7 @@ export const handleViewCategory = async (req, res, next) => {
 
 
         const taskCategories = await getCategoriesByUser(userId); // 서비스 호출
-        res.success(taskCategories); // 성공 응답
+        res.success(transformCategoryListResponse(taskCategories)); // 성공 응답
     } catch (error) {
         next(error); // 전역 오류 처리 미들웨어로 전달
     }
@@ -395,7 +402,7 @@ export const handleCreateTaskCategoryBulk = async (req, res, next) => {
         return res.status(200).json({
             resultType: "SUCCESS",
             error: null,
-            success: createdTaskCategory,
+            success: transformTaskResponse(createdTaskCategory),
         });
     } catch (error) {
         next(error); // 전역 오류 처리 미들웨어로 전달
diff --git a/src/controllers/task.controller.js b/src/controllers/task.controller.js
index a143ba3..808f090 100644
--- a/src/controllers/task.controller.js
+++ b/src/controllers/task.controller.js
@@ -1,6 +1,8 @@
 import { StatusCodes } from "http-status-codes";
 import { createTask,createTaskBulk} from "../services/task.service.js";
-import { createTaskBulkDto, createTaskDto, getTaskDto, responseFromToggledTask, updateTaskDto } from "../dtos/task.dto.js";
+import { createTaskBulkDto, createTaskDto, getTaskDto, responseFromToggledTask, updateTaskDto,
+    transformTaskListResponse, transformTaskResponse
+} from "../dtos/task.dto.js";
 import { updateTask, getTask, deleteTask } from "../services/task.service.js";
 import { toggleTaskCompletion } from "../services/task.service.js";
 import { findTaskWithPlanner } from "../repositories/task.repository.js";
@@ -57,7 +59,7 @@ export const handleCreateTask = async (req, res, next) => {
         const newTask = await createTask({ ...validTaskData, userId });
 
         // 성공 응답 반환
-        res.success(newTask);
+        res.success(transformTaskResponse(newTask));
 
     } catch (error) {
         next(error);
@@ -110,7 +112,7 @@ export const handleCreateTaskBulk = async (req, res, next) => {
         //여러개 생성 
         const newTasks= await createTaskBulk (validTaskData, userId);
 
-        res.success(newTasks);
+        res.success(transformTaskListResponse(newTasks));
    } catch (error) {
         next(error);
    }
@@ -185,7 +187,7 @@ export const handleUpdateTask = async (req, res, next) => {
         });
 
         // 성공 응답
-        res.success(updatedTask);
+        res.success(transformTaskResponse(updatedTask));
     } catch (error) {
         next(error);
     }
@@ -223,7 +225,7 @@ export const handleGetTask = async (req, res, next) => {
         
         const tasks = await getTask(validDate, userId);
         
-        res.success(tasks);
+        res.success(transformTaskListResponse(tasks));
     }
     catch (error) {
         console.log(error);
diff --git a/src/dtos/task.dto.js b/src/dtos/task.dto.js
index 1025032..d03d424 100644
--- a/src/dtos/task.dto.js
+++ b/src/dtos/task.dto.js
@@ -1,3 +1,35 @@
+// YYYY-MM-DDTHH:mm:ss.sssZ 형식으로 변환하는 함수 (UTC+9 적용)
+const formatDateTime = (date) => {
+    if (!date) return null;
+    const validDate = date instanceof Date ? date : new Date(date); // 문자열이면 Date 객체로 변환
+    if (isNaN(validDate.getTime())) {
+        console.error("Invalid date detected:", date);
+        return null;
+    }
+    const KST = new Date(validDate.getTime() + 9 * 60 * 60 * 1000); // UTC+9 적용
+    return KST.toISOString(); // ISO 형식 유지
+};
+
+export const transformCategoryResponse = (category) => ({
+    ...category,
+    createdAt: formatDateTime(category.createdAt),
+    updatedAt: formatDateTime(category.updatedAt)
+});
+
+export const transformCategoryListResponse = (categories) =>
+    Array.isArray(categories) ? categories.map(transformCategoryResponse) : categories;
+
+
+export const transformTaskResponse = (task) => ({
+    ...task,
+    createdAt: formatDateTime(task.createdAt),
+    updatedAt: formatDateTime(task.updatedAt)
+});
+
+export const transformTaskListResponse = (tasks) =>
+    tasks.map(transformTaskResponse);
+
+
 export const createTaskDto = (body) => {
 
     // 1. Validate title