diff --git a/Assets/VRM10/Runtime/Components/Vrm10Runtime/Vrm10RuntimeSpringBone .cs b/Assets/VRM10/Runtime/Components/Vrm10Runtime/Vrm10RuntimeSpringBone .cs
index 06863b2fc..9e5e82d55 100644
--- a/Assets/VRM10/Runtime/Components/Vrm10Runtime/Vrm10RuntimeSpringBone .cs	
+++ b/Assets/VRM10/Runtime/Components/Vrm10Runtime/Vrm10RuntimeSpringBone .cs	
@@ -28,7 +28,7 @@ namespace UniVRM10
             set { m_fastSpringBoneBuffer.IsSpringBoneEnabled = value; }
         }
 
-        public Vrm10RuntimeSpringBone(Vrm10Instance instance)
+        internal Vrm10RuntimeSpringBone(Vrm10Instance instance)
         {
             m_instance = instance;