diff --git a/core/service.go b/core/service.go
index dc123dc..c5f8210 100644
--- a/core/service.go
+++ b/core/service.go
@@ -296,6 +296,32 @@ func (sh *serviceDescription) link(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	bfinfo, err := sh.getUserBrowserInfo(r)
+	if err != nil {
+		logger.Error("getUserBrowserInfo failed :", err)
+		w.WriteHeader(http.StatusBadRequest)
+		return
+	}
+
+	guestlink := (oldAuth.Platform == "guest")
+	if !guestlink {
+		_, err = sh.readProfile(oldType, oldId, bfinfo)
+		if err != nil {
+			logger.Error("readProfile(old) failed :", err)
+			w.WriteHeader(http.StatusBadRequest)
+			return
+		}
+	} else {
+		logger.Println("from guest acc to real acc link : ", oldId, bfinfo, newType, newId, bfinfo)
+	}
+
+	oldType, oldId, err = sh.getProviderInfo(oldType, oldId)
+	if err != nil {
+		logger.Error("getProviderInfo failed :", err)
+		w.WriteHeader(http.StatusBadRequest)
+		return
+	}
+
 	// fmt.Println("=================")
 	// fmt.Println(oldType)
 	// fmt.Println(oldId)
@@ -314,20 +340,6 @@ func (sh *serviceDescription) link(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	bfinfo, err := sh.getUserBrowserInfo(r)
-	if err != nil {
-		logger.Error("getUserBrowserInfo failed :", err)
-		w.WriteHeader(http.StatusBadRequest)
-		return
-	}
-
-	_, err = sh.readProfile(oldType, oldId, bfinfo)
-	if err != nil {
-		logger.Error("readProfile(old) failed :", err)
-		w.WriteHeader(http.StatusBadRequest)
-		return
-	}
-
 	email, err := sh.readProfile(newType, newId, bfinfo)
 	if err != nil {
 		logger.Error("readProfile(new) failed :", err)
@@ -345,6 +357,7 @@ func (sh *serviceDescription) link(w http.ResponseWriter, r *http.Request) {
 	if err != nil {
 		logger.Error("getProviderInfo failed :", err)
 		w.WriteHeader(http.StatusBadRequest)
+		return
 	}
 
 	createtime := primitive.NewDateTimeFromTime(time.Now().UTC())
@@ -385,6 +398,20 @@ func (sh *serviceDescription) link(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	if guestlink {
+		//기존 게스트 링크 삭제
+		link, err = sh.mongoClient.FindOneAndDelete(CollectionLink, bson.M{
+			"platform": oldType,
+			"uid":      oldId,
+		}, options.FindOneAndDelete().SetProjection(bson.M{"_id": 1}))
+
+		if err == nil {
+			sh.mongoClient.Delete(CollectionAccount, bson.M{
+				"_id": link["_id"].(primitive.ObjectID),
+			})
+		}
+	}
+
 	logger.Println("link success :", r.URL.Query())
 }