diff --git a/projects/ucap-webmessenger-app/src/app/layouts/messenger/components/messages.component.ts b/projects/ucap-webmessenger-app/src/app/layouts/messenger/components/messages.component.ts
index de308179..935fb921 100644
--- a/projects/ucap-webmessenger-app/src/app/layouts/messenger/components/messages.component.ts
+++ b/projects/ucap-webmessenger-app/src/app/layouts/messenger/components/messages.component.ts
@@ -1588,7 +1588,32 @@ export class MessagesComponent implements OnInit, OnDestroy, AfterViewInit {
         break;
       case 'ADD_MEMBER':
         {
-          const curRoomUser = this.userInfoListSubject.value.filter(
+          const userInfoList = this.userInfoListSubject.value;
+          if (
+            !!userInfoList &&
+            userInfoList.length >=
+              environment.productConfig.CommonSetting.maxChatRoomUser
+          ) {
+            this.dialogService.open<
+              AlertDialogComponent,
+              AlertDialogData,
+              AlertDialogResult
+            >(AlertDialogComponent, {
+              data: {
+                title: this.translateService.instant('chat.errors.label'),
+                html: this.translateService.instant(
+                  'chat.errors.maxCountOfRoomMemberWith',
+                  {
+                    maxCount:
+                      environment.productConfig.CommonSetting.maxChatRoomUser
+                  }
+                )
+              }
+            });
+            return;
+          }
+
+          const curRoomUser = userInfoList.filter(
             user =>
               user.seq !== this.loginResSubject.value.userSeq && user.isJoinRoom
           );
diff --git a/projects/ucap-webmessenger-app/src/app/layouts/messenger/components/right-drawer/room-user-list.component.ts b/projects/ucap-webmessenger-app/src/app/layouts/messenger/components/right-drawer/room-user-list.component.ts
index a7511be1..647c15aa 100644
--- a/projects/ucap-webmessenger-app/src/app/layouts/messenger/components/right-drawer/room-user-list.component.ts
+++ b/projects/ucap-webmessenger-app/src/app/layouts/messenger/components/right-drawer/room-user-list.component.ts
@@ -21,7 +21,10 @@ import {
   DialogService,
   ConfirmDialogComponent,
   ConfirmDialogResult,
-  ConfirmDialogData
+  ConfirmDialogData,
+  AlertDialogComponent,
+  AlertDialogData,
+  AlertDialogResult
 } from '@ucap-webmessenger/ui';
 import {
   SelectGroupDialogComponent,
@@ -43,6 +46,7 @@ import { LoginResponse } from '@ucap-webmessenger/protocol-authentication';
 import { MatDialog } from '@angular/material/dialog';
 import { MatMenuTrigger } from '@angular/material/menu';
 import { TranslateService } from '@ngx-translate/core';
+import { environment } from 'projects/ucap-webmessenger-app/src/environments/environment.dev';
 
 @Component({
   selector: 'app-layout-chat-right-drawer-room-user-list',
@@ -139,6 +143,29 @@ export class RoomUserListComponent implements OnInit, OnDestroy {
   }
 
   async onClickAddMember() {
+    if (
+      !!this.userInfoList &&
+      this.userInfoList.length >=
+        environment.productConfig.CommonSetting.maxChatRoomUser
+    ) {
+      this.dialogService.open<
+        AlertDialogComponent,
+        AlertDialogData,
+        AlertDialogResult
+      >(AlertDialogComponent, {
+        data: {
+          title: this.translateService.instant('chat.errors.label'),
+          html: this.translateService.instant(
+            'chat.errors.maxCountOfRoomMemberWith',
+            {
+              maxCount: environment.productConfig.CommonSetting.maxChatRoomUser
+            }
+          )
+        }
+      });
+      return;
+    }
+
     const curRoomUser = this.userInfoList.filter(
       user => user.seq !== this.loginRes.userSeq && user.isJoinRoom
     );
diff --git a/projects/ucap-webmessenger-app/src/app/store/messenger/room/effects.ts b/projects/ucap-webmessenger-app/src/app/store/messenger/room/effects.ts
index 9cf07234..5caa44ff 100644
--- a/projects/ucap-webmessenger-app/src/app/store/messenger/room/effects.ts
+++ b/projects/ucap-webmessenger-app/src/app/store/messenger/room/effects.ts
@@ -5,6 +5,8 @@ import { Actions, createEffect, ofType } from '@ngrx/effects';
 import { Store, select } from '@ngrx/store';
 
 import { NGXLogger } from 'ngx-logger';
+import { environment } from '../../../../environments/environment';
+
 import { of } from 'rxjs';
 import {
   tap,
@@ -79,6 +81,8 @@ import {
   AlertDialogData,
   AlertDialogResult
 } from '@ucap-webmessenger/ui';
+import { ActivatedRouteSnapshot } from '@angular/router';
+import { TranslateService } from '@ngx-translate/core';
 
 @Injectable()
 export class Effects {
@@ -285,6 +289,29 @@ export class Effects {
         )
       ),
       exhaustMap(([action, roomInfo]) => {
+        if (
+          environment.productConfig.CommonSetting.maxChatRoomUser <
+          action.req.userSeqs.length
+        ) {
+          this.dialogService.open<
+            AlertDialogComponent,
+            AlertDialogData,
+            AlertDialogResult
+          >(AlertDialogComponent, {
+            data: {
+              title: this.translateService.instant('chat.errors.label'),
+              html: this.translateService.instant(
+                'chat.errors.maxCountOfRoomMemberWith',
+                {
+                  maxCount:
+                    environment.productConfig.CommonSetting.maxChatRoomUser
+                }
+              )
+            }
+          });
+          return of(inviteFailure({ error: 'over size room users !!' }));
+        }
+
         if (roomInfo.roomType === RoomType.Single) {
           // Re Open
           return this.roomProtocolService.open(action.req).pipe(
@@ -454,6 +481,7 @@ export class Effects {
     private store: Store<any>,
     private roomProtocolService: RoomProtocolService,
     private sessionStorageService: SessionStorageService,
+    private translateService: TranslateService,
     private dialogService: DialogService,
     private logger: NGXLogger
   ) {}