diff --git a/src/chat/repositories/chat.repository.ts b/src/chat/repositories/chat.repository.ts
index 20a009d..e5cdb74 100644
--- a/src/chat/repositories/chat.repository.ts
+++ b/src/chat/repositories/chat.repository.ts
@@ -76,7 +76,7 @@ export class ChatRepository {
 
     // 채팅방을 나갔으면 그 이후의 메세지만 조회
     if (leftAt) {
-      whereConditions.created_at = { gt: leftAt };
+      whereConditions.sent_at = { gt: leftAt };
     }
 
     const [messages, totalCount] = await Promise.all([
@@ -105,6 +105,7 @@ export class ChatRepository {
     return {
       messages: actualMessages,
       totalCount,
+      hasMore: hasNextPage,
     };
   }
 
@@ -258,14 +259,16 @@ export class ChatRepository {
   }
 
   // == 메세지 저장
-  async saveMessage(
-    roomId: number,
-    senderId: number,
-    content: string,
-    files: { url: string; contentType: AttachmentType; name: string; size: number }[]
-  ) {
-
-    return prisma.chatMessage.create({
+async saveMessage(
+  roomId: number,
+  senderId: number,
+  content: string,
+  files: { url: string; contentType: AttachmentType; name: string; size: number }[]
+) {
+  // 트랜잭션으로 메세지 생성과 채팅방 업데이트를 묶어서 처리
+  return prisma.$transaction(async (tx) => {
+    // 1. 메세지 생성
+    const savedMessage = await tx.chatMessage.create({
       data: {
         room_id: roomId,
         sender_id: senderId,
@@ -290,8 +293,14 @@ export class ChatRepository {
         attachments: true,
       },
     });
-  }
 
-  
-}
+    // 2. 채팅방의 마지막 메세지 ID 업데이트
+    await tx.chatRoom.update({
+      where: { room_id: roomId },
+      data: { last_message_id: savedMessage.message_id },
+    });
 
+    return savedMessage;
+  });
+}
+}
diff --git a/src/chat/services/chat.service.ts b/src/chat/services/chat.service.ts
index 9e313a1..87d5302 100644
--- a/src/chat/services/chat.service.ts
+++ b/src/chat/services/chat.service.ts
@@ -63,10 +63,9 @@ export class ChatService {
       this.chatRepo.findMessagesByRoomId(roomId, cursor, limit, myId),
       updateReadStatus
     ]);
-    
-    // 페이지네이션 
-    const hasMore = messageInfo.messages.length > limit;
-    const messages = hasMore ? messageInfo.messages.slice(0, limit) : messageInfo.messages;
+
+    const hasMore = messageInfo.hasMore; 
+    const messages = messageInfo.messages;
 
     return ChatRoomDetailResponseDto.from({
       roomDetail,
@@ -88,7 +87,6 @@ export class ChatService {
         filter,
         search
       });
-
     
     // 페이지네이션 
     const hasMore = roomList.rooms.length > limit;