diff --git a/src/main/java/com/example/cosmos_serversb/entities/Group.java b/src/main/java/com/example/cosmos_serversb/entities/Group.java
index 4c98291..7b2805b 100644
--- a/src/main/java/com/example/cosmos_serversb/entities/Group.java
+++ b/src/main/java/com/example/cosmos_serversb/entities/Group.java
@@ -1,7 +1,9 @@
 //このクラスは仮です
 package com.example.cosmos_serversb.entities;
 
+import com.example.cosmos_serversb.models.SessionManager;
 import com.example.cosmos_serversb.models.Users;
+import org.hibernate.Session;
 
 import java.util.ArrayList;
 import java.util.HashSet;
@@ -87,8 +89,14 @@
     public void addMember(String uId){
         // User user = new User(uId, uId, "http:test", "hogehoge");
         User user = Users.getInstance().getUserById(uId);
-        members.add(user);
-//        user.addGroups(this);
+        if(user != null) {
+            members.add(user);
+            user.addGroups(this);
+            Session session = SessionManager.getInstance().getSession();
+            session.update(user);
+        }else{
+            //例外処理
+        }
     }
 
 }