diff --git a/core/group_instant.go b/core/group_instant.go
index d538fad..af82e01 100644
--- a/core/group_instant.go
+++ b/core/group_instant.go
@@ -162,6 +162,7 @@ func (gi *groupInstant) join(gd *instantDoc, mid primitive.ObjectID, character a
 	if err != nil {
 		return err
 	}
+	delete(memdoc, "_id")
 
 	// 기존 유저에게 새 유저 알림
 	gi.sendUpstreamMessage(&wshandler.UpstreamMessage{
@@ -174,10 +175,18 @@ func (gi *groupInstant) join(gd *instantDoc, mid primitive.ObjectID, character a
 
 	gi.rh.JSONSet(mid.Hex(), "$.instant", bson.M{"id": gd.strid()})
 
+	full := gd.loadFull()
+	if f, ok := full["_members"]; ok {
+		members := f.(map[string]any)
+		for _, char := range members {
+			delete(char.(map[string]any), "_id")
+		}
+	}
+
 	// 최초 입장이라면 새 멤버에 그룹 전체를 알림
 	gi.sendUpstreamMessage(&wshandler.UpstreamMessage{
 		Target: mid.Hex(),
-		Body:   gd.loadFull(),
+		Body:   full,
 		Tag:    []string{"GroupDocFull"},
 	})
 	gi.enterRoom(gd.Gid, mid)
@@ -215,14 +224,17 @@ func (gi *groupInstant) UpdateInstantDocument(w http.ResponseWriter, r *http.Req
 	})
 
 	if data.Result == "after" {
-		raws, err := gi.rh.JSONGetDocuments(data.Gid.Hex(), "$")
-		if err != nil {
-			logger.Println("QueryInstantDocument failed. JSONGetDocuments returns err :", err)
-			w.WriteHeader(http.StatusInternalServerError)
-			return
+		fulldoc := gd.loadFull()
+		if fulldoc != nil {
+			tids := fulldoc["_members"].(map[string]any)
+			mids := make(map[string]any)
+			for k, v := range tids {
+				mid := midFromTid(data.Gid, k)
+				mids[mid.Hex()] = v
+			}
+			fulldoc["_members"] = mids
 		}
-
-		gocommon.MakeEncoder(w, r).Encode(raws[0])
+		gocommon.MakeEncoder(w, r).Encode(fulldoc)
 	}
 }