diff --git a/src/main/java/ita/tinybite/domain/chat/dto/GroupChatRoomDetailResDto.java b/src/main/java/ita/tinybite/domain/chat/dto/GroupChatRoomDetailResDto.java
index d7598f0..da514c8 100644
--- a/src/main/java/ita/tinybite/domain/chat/dto/GroupChatRoomDetailResDto.java
+++ b/src/main/java/ita/tinybite/domain/chat/dto/GroupChatRoomDetailResDto.java
@@ -1,7 +1,33 @@
 package ita.tinybite.domain.chat.dto;
 
+import ita.tinybite.domain.chat.entity.ChatRoom;
+import ita.tinybite.domain.party.enums.PartyStatus;
 import lombok.Builder;
 
 @Builder
-public record GroupChatRoomDetailResDto() {
+public record GroupChatRoomDetailResDto(
+        Long groupChatRoomId,
+        Long partyId,
+        String partyTitle,
+        PartyStatus status,
+        int currentParticipantCnt,
+        int maxParticipantCnt,
+        String formattedPartyCnt
+) {
+    public static GroupChatRoomDetailResDto of(ChatRoom groupChatRoom) {
+        return GroupChatRoomDetailResDto.builder()
+                .groupChatRoomId(groupChatRoom.getId())
+                .partyId(groupChatRoom.getParty().getId())
+                .partyTitle(groupChatRoom.getParty().getTitle())
+                .status(groupChatRoom.getParty().getStatus())
+                .currentParticipantCnt(groupChatRoom.getParty().getCurrentParticipants())
+                .maxParticipantCnt(groupChatRoom.getParty().getMaxParticipants())
+                .formattedPartyCnt(formatParticipantStatus(groupChatRoom.getParty().getCurrentParticipants(), groupChatRoom.getParty().getMaxParticipants()))
+                .build();
+    }
+
+    private static String formatParticipantStatus(int current, int max) {
+        return String.format("%d/%d명", current, max);
+    }
+
 }
diff --git a/src/main/java/ita/tinybite/domain/chat/dto/res/OneToOneChatRoomDetailResDto.java b/src/main/java/ita/tinybite/domain/chat/dto/res/OneToOneChatRoomDetailResDto.java
index 45cfc49..401b886 100644
--- a/src/main/java/ita/tinybite/domain/chat/dto/res/OneToOneChatRoomDetailResDto.java
+++ b/src/main/java/ita/tinybite/domain/chat/dto/res/OneToOneChatRoomDetailResDto.java
@@ -40,12 +40,12 @@ public static OneToOneChatRoomDetailResDto of(Party party, PartyParticipant part
 
         switch(participantStatus) {
             case PENDING -> {
-                if(type.equals(ParticipantType.PARTICIPANT)) {
+                if(type.equals(ParticipantType.HOST)) { // type = HOST
                     resDtoBuilder
                             .participantStatus(ParticipantStatus.REQUESTED)
                             .targetProfileImage(targetUser.getProfileImage())
                             .targetLocation(targetUser.getLocation());
-                } else { // type = HOST
+                } else { // type = PARTICIPANT
                     resDtoBuilder
                             .participantStatus(ParticipantStatus.PENDING);
                 }
diff --git a/src/main/java/ita/tinybite/domain/chat/service/ChatRoomService.java b/src/main/java/ita/tinybite/domain/chat/service/ChatRoomService.java
index 64fd3a7..0cbbd37 100644
--- a/src/main/java/ita/tinybite/domain/chat/service/ChatRoomService.java
+++ b/src/main/java/ita/tinybite/domain/chat/service/ChatRoomService.java
@@ -17,6 +17,8 @@
 import ita.tinybite.domain.party.enums.ParticipantStatus;
 import ita.tinybite.domain.party.repository.PartyParticipantRepository;
 import ita.tinybite.domain.user.entity.User;
+import ita.tinybite.global.exception.BusinessException;
+import ita.tinybite.global.exception.errorcode.ChatRoomErrorCode;
 import lombok.RequiredArgsConstructor;
 import org.springframework.data.domain.Limit;
 import org.springframework.stereotype.Service;
@@ -101,21 +103,21 @@ public List<GroupChatRoomResDto> getGroupRooms() {
     public OneToOneChatRoomDetailResDto getOneToOneRoom(Long chatRoomId) {
         User currentUser = securityProvider.getCurrentUser();
         ChatRoom chatRoom = chatRoomRepository.findById(chatRoomId).orElseThrow();
-        PartyParticipant partyParticipant = partyParticipantRepository.findByOneToOneChatRoom(chatRoom).orElseThrow();
 
-        ChatRoom groupChatRoom = chatRoomRepository.findByPartyAndType(chatRoom.getParty(), ChatRoomType.GROUP).orElseGet(null);
-
-        User host = chatRoom.getParty().getHost();
-        host.getNickname();
+        if(!chatRoom.getType().equals(ChatRoomType.ONE_TO_ONE)) throw BusinessException.of(ChatRoomErrorCode.NOT_ONE_TO_ONE);
 
-        User targetUser = partyParticipant.getUser();
-        targetUser.getNickname();
+        PartyParticipant partyParticipant = partyParticipantRepository.findByOneToOneChatRoomAndStatus(chatRoom, ParticipantStatus.PENDING);
 
+        ChatRoom groupChatRoom = chatRoomRepository.findByPartyAndType(chatRoom.getParty(), ChatRoomType.GROUP).orElseGet(null);
         return OneToOneChatRoomDetailResDto.of(chatRoom.getParty(), partyParticipant, currentUser, groupChatRoom);
     }
 
     public GroupChatRoomDetailResDto getGroupRoom(Long chatRoomId) {
-        return null;
+        ChatRoom chatRoom = chatRoomRepository.findById(chatRoomId).orElseThrow();
+
+        if(!chatRoom.getType().equals(ChatRoomType.GROUP)) throw BusinessException.of(ChatRoomErrorCode.NOT_GROUP);
+
+        return GroupChatRoomDetailResDto.of(chatRoom);
     }
 
     private static String getTimeAgo(LocalDateTime then) {
diff --git a/src/main/java/ita/tinybite/domain/party/repository/PartyParticipantRepository.java b/src/main/java/ita/tinybite/domain/party/repository/PartyParticipantRepository.java
index 7366746..18bc945 100644
--- a/src/main/java/ita/tinybite/domain/party/repository/PartyParticipantRepository.java
+++ b/src/main/java/ita/tinybite/domain/party/repository/PartyParticipantRepository.java
@@ -91,8 +91,10 @@ boolean existsByParty_IdAndUser_UserIdAndStatus(
         ParticipantStatus status
     );
   
-    @Query("SELECT pp FROM PartyParticipant pp WHERE pp.party.id = :partyId AND pp.user.id = :userId")
+    @Query("SELECT pp FROM PartyParticipant pp WHERE pp.party.id = :partyId AND pp.user.userId = :userId")
     Optional<PartyParticipant> findByPartyIdAndUserId(@Param("partyId") Long partyId, @Param("userId") Long userId);
 
     Optional<PartyParticipant> findByOneToOneChatRoom(ChatRoom oneToOneChatRoom);
+
+    PartyParticipant findByOneToOneChatRoomAndStatus(ChatRoom oneToOneChatRoom, ParticipantStatus status);
 }
\ No newline at end of file
diff --git a/src/main/java/ita/tinybite/global/exception/errorcode/ChatRoomErrorCode.java b/src/main/java/ita/tinybite/global/exception/errorcode/ChatRoomErrorCode.java
new file mode 100644
index 0000000..fd5b811
--- /dev/null
+++ b/src/main/java/ita/tinybite/global/exception/errorcode/ChatRoomErrorCode.java
@@ -0,0 +1,23 @@
+package ita.tinybite.global.exception.errorcode;
+
+import lombok.Getter;
+import org.springframework.http.HttpStatus;
+
+@Getter
+public enum ChatRoomErrorCode implements ErrorCode {
+
+    NOT_ONE_TO_ONE(HttpStatus.BAD_REQUEST, "NOT_ONE_TO_ONE", "일대일 채팅이 아닙니다."),
+    NOT_GROUP(HttpStatus.BAD_REQUEST, "NOT_GROUP", "그룹 채팅이 아닙니다."),
+
+    ;
+
+    private final HttpStatus httpStatus;
+    private final String code;
+    private final String message;
+
+    ChatRoomErrorCode(HttpStatus httpStatus, String code, String message) {
+        this.httpStatus = httpStatus;
+        this.code = code;
+        this.message = message;
+    }
+}