diff --git a/core/maingate.go b/core/maingate.go
index 2066cd8..19c7f01 100644
--- a/core/maingate.go
+++ b/core/maingate.go
@@ -787,13 +787,18 @@ func (mg *Maingate) getProviderInfo(platform string, uid string) (string, string
 		if provider == "" || providerid == "" {
 			return "", "", errors.New("getProviderInfo - firebase info not found: " + provider + " / " + providerid)
 		}
+	case "":
+		//guest auth
+		providerid = uid
+		if providerid == "" {
+			return "", "", errors.New("getProviderInfo - guest provider id not found: " + provider + " / " + providerid)
+		}
 	default:
 		provider = platform
 		providerid = uid
-	}
-
-	if provider == "" || providerid == "" {
-		return "", "", errors.New("getProviderInfo - provider info not found: " + provider + " / " + providerid)
+		if provider == "" || providerid == "" {
+			return "", "", errors.New("getProviderInfo - provider info not found: " + provider + " / " + providerid)
+		}
 	}
 
 	return provider, providerid, nil
diff --git a/core/service.go b/core/service.go
index 85098ee..453a8c9 100644
--- a/core/service.go
+++ b/core/service.go
@@ -420,6 +420,17 @@ func (sh *serviceDescription) link(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	if guestlink {
+		//기존 게스트 링크 삭제
+		guestLinkId, err := primitive.ObjectIDFromHex(oldId)
+		if err == nil {
+			_, err = sh.mongoClient.Delete(CollectionLink, bson.M{
+				"platform": oldType,
+				"_id":      guestLinkId,
+			})
+		}
+	}
+
 	logger.Println("link success :", r.URL.Query())
 }