diff --git a/packages/backend/src/chat/chat.gateway.ts b/packages/backend/src/chat/chat.gateway.ts
index 65474edb..0fd6a1f0 100644
--- a/packages/backend/src/chat/chat.gateway.ts
+++ b/packages/backend/src/chat/chat.gateway.ts
@@ -35,7 +35,7 @@ interface chatResponse {
   createdAt: Date;
 }
 
-@WebSocketGateway({ namespace: 'chat' })
+@WebSocketGateway({ namespace: '/api/chat/realtime' })
 @UseFilters(WebSocketExceptionFilter)
 export class ChatGateway implements OnGatewayConnection {
   @WebSocketServer()
diff --git a/packages/backend/src/chat/chat.service.ts b/packages/backend/src/chat/chat.service.ts
index c9431a8d..fbb5ac45 100644
--- a/packages/backend/src/chat/chat.service.ts
+++ b/packages/backend/src/chat/chat.service.ts
@@ -1,8 +1,10 @@
 import { BadRequestException, Injectable } from '@nestjs/common';
-import { DataSource, SelectQueryBuilder } from 'typeorm';
+import { WsException } from '@nestjs/websockets';
+import { DataSource, EntityManager, SelectQueryBuilder } from 'typeorm';
 import { Chat } from '@/chat/domain/chat.entity';
 import { ChatScrollQuery } from '@/chat/dto/chat.request';
 import { ChatScrollResponse } from '@/chat/dto/chat.response';
+import { UserStock } from '@/stock/domain/userStock.entity';
 
 export interface ChatMessage {
   message: string;
@@ -23,10 +25,15 @@ export class ChatService {
   constructor(private readonly dataSource: DataSource) {}
 
   async saveChat(userId: number, chatMessage: ChatMessage) {
-    return this.dataSource.manager.save(Chat, {
-      user: { id: userId },
-      stock: { id: chatMessage.stockId },
-      message: chatMessage.message,
+    return this.dataSource.transaction(async (manager) => {
+      if (!(await this.hasStock(userId, chatMessage.stockId, manager))) {
+        throw new WsException('not have stock');
+      }
+      return manager.save(Chat, {
+        user: { id: userId },
+        stock: { id: chatMessage.stockId },
+        message: chatMessage.message,
+      });
     });
   }
 
@@ -57,6 +64,12 @@ export class ChatService {
     return queryBuilder.getMany();
   }
 
+  private hasStock(userId: number, stockId: string, manager: EntityManager) {
+    return manager.exists(UserStock, {
+      where: { user: { id: userId }, stock: { id: stockId } },
+    });
+  }
+
   private validatePageSize(chatScrollQuery: ChatScrollQuery) {
     const { pageSize } = chatScrollQuery;
     if (pageSize && pageSize > 100) {
diff --git a/packages/backend/src/stock/stock.gateway.ts b/packages/backend/src/stock/stock.gateway.ts
index cf98907c..1f4ab32d 100644
--- a/packages/backend/src/stock/stock.gateway.ts
+++ b/packages/backend/src/stock/stock.gateway.ts
@@ -1,14 +1,14 @@
 import {
+  ConnectedSocket,
+  MessageBody,
+  SubscribeMessage,
   WebSocketGateway,
   WebSocketServer,
-  SubscribeMessage,
-  MessageBody,
-  ConnectedSocket,
 } from '@nestjs/websockets';
 import { Server, Socket } from 'socket.io';
 
 @WebSocketGateway({
-  namespace: '/stock/realtime',
+  namespace: '/api/stock/realtime',
 })
 export class StockGateway {
   @WebSocketServer()