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 eb988d8..e774568 100644
--- a/src/main/java/com/example/cosmos_serversb/entities/Group.java
+++ b/src/main/java/com/example/cosmos_serversb/entities/Group.java
@@ -78,6 +78,10 @@
         return members;
     }
 
+    public void deleteMember(User user){
+        members.remove(user);
+    }
+
     public void clearAllMembersForDeleteGroup(){
         members.clear();
     }
@@ -96,10 +100,7 @@
     }
 
     public boolean equals(Group group) {
-        if(this.gId == group.getgId()){
-            return true;
-        }
-        return false;
+        return this.gId.equals(group.getgId());
     }
 
 }
diff --git a/src/main/java/com/example/cosmos_serversb/entities/User.java b/src/main/java/com/example/cosmos_serversb/entities/User.java
index 592d2ea..7315afe 100644
--- a/src/main/java/com/example/cosmos_serversb/entities/User.java
+++ b/src/main/java/com/example/cosmos_serversb/entities/User.java
@@ -135,9 +135,6 @@
     }
 
     public boolean equals(User user) {
-        if(this.uId == user.getuId()){
-            return true;
-        }
-        return false;
+        return uId.equals(user.getuId());
     }
 }
\ No newline at end of file
diff --git a/src/main/java/com/example/cosmos_serversb/models/Groups.java b/src/main/java/com/example/cosmos_serversb/models/Groups.java
index 0b57aa5..13cf036 100644
--- a/src/main/java/com/example/cosmos_serversb/models/Groups.java
+++ b/src/main/java/com/example/cosmos_serversb/models/Groups.java
@@ -104,8 +104,22 @@
         return null;
     }
 
-    public static HashMap<String, String> deleteMember(String gId, String uId){
-        return null;
+    public static DeleteResult deleteMember(String gId, String uId){
+        Session session = SessionManager.getInstance().getSession();
+        Group editGroup = session.get(Group.class, gId);
+        User editUser = session.get(User.class, uId);
+        if(editGroup != null){
+            if(editGroup.getMembers().contains(editUser)){
+                editUser.exitGroup(editGroup);
+                editGroup.deleteMember(editUser);
+                if(editGroup.getMembers().size() == 0){
+                    //ユーザーが存在しないグループは削除
+                    session.delete(editGroup);
+                }
+                return DeleteResult.SUCCESS;
+            }
+        }
+        return DeleteResult.FAILURE;
     }
 
     /*