diff --git a/Assets/VRM10/Runtime/Components/Vrm10Instance/Vrm10Instance.cs b/Assets/VRM10/Runtime/Components/Vrm10Instance/Vrm10Instance.cs
index daee18e60..3edce1673 100644
--- a/Assets/VRM10/Runtime/Components/Vrm10Instance/Vrm10Instance.cs
+++ b/Assets/VRM10/Runtime/Components/Vrm10Instance/Vrm10Instance.cs
@@ -117,6 +117,12 @@ namespace UniVRM10
 
         internal Vrm10Runtime MakeRuntime(bool useControlRig)
         {
+            if (m_springBoneRuntime == null)
+            {
+                // deafult に fallback
+                // TODO: scene に配置した prefab に SpringRuntime をカスタムする手段
+                m_springBoneRuntime = new Vrm10FastSpringboneRuntime();
+            }
             return new Vrm10Runtime(this, useControlRig, m_springBoneRuntime);
         }