diff --git a/Assets/UniGLTF/Editor/UniGLTF/ScriptedImporter/ScriptedImporterImpl.cs b/Assets/UniGLTF/Editor/UniGLTF/ScriptedImporter/ScriptedImporterImpl.cs
index 0127f308d..ac9897aaf 100644
--- a/Assets/UniGLTF/Editor/UniGLTF/ScriptedImporter/ScriptedImporterImpl.cs
+++ b/Assets/UniGLTF/Editor/UniGLTF/ScriptedImporter/ScriptedImporterImpl.cs
@@ -17,15 +17,42 @@ namespace UniGLTF
         public static void Import(ScriptedImporter scriptedImporter, AssetImportContext context, Axises reverseAxis)
         {
 #if VRM_DEVELOP            
-            Debug.Log("OnImportAsset to " + context.assetPath);
+            Debug.Log("OnImportAsset to " + scriptedImporter.assetPath);
 #endif
 
-            var loaded = Load(context.assetPath,
-                scriptedImporter.GetExternalObjectMap(),
-                reverseAxis
-            );
+            //
+            // Parse(parse glb, parser gltf json)
+            //
+            var parser = new GltfParser();
+            parser.ParsePath(scriptedImporter.assetPath);
 
-            AddSubAssets(context, loaded);
+            //
+            // Import(create unity objects)
+            //
+            var externalObjectMap = scriptedImporter.GetExternalObjectMap();
+
+            using (var loaded = new ImporterContext(parser, null,
+                externalObjectMap.Where(x => x.Value != null).Select(x => (x.Value.name, x.Value)).Concat(
+                EnumerateExists(externalObjectMap, parser, UnityPath.FromUnityPath(scriptedImporter.assetPath).Parent))))
+            {
+                loaded.InvertAxis = reverseAxis;
+                loaded.Load();
+                loaded.ShowMeshes();
+
+                loaded.TransferOwnership(o =>
+                {
+#if VRM_DEVELOP
+                    Debug.Log($"[{o.GetType().Name}] {o.name} will not destroy");
+#endif
+
+                    context.AddObjectToAsset(o.name, o);
+                    if (o is GameObject)
+                    {
+                        // Root GameObject is main object
+                        context.SetMainObject(loaded.Root);
+                    }
+                });
+            }
         }
 
         static IEnumerable<(string, UnityEngine.Object)> EnumerateExists(Dictionary<AssetImporter.SourceAssetIdentifier, UnityEngine.Object> exclude,
@@ -58,83 +85,5 @@ namespace UniGLTF
                 }
             }
         }
-
-        /// <summary>
-        /// Parse して、UnityObject 化する。
-        /// 
-        /// TODO: すべての UnityObject を ImporterContext が所有する。(Disposeで削除できる)
-        /// </summary>
-        /// <param name="assetPath">glbのパス</param>
-        /// <param name="externalObjectMap">ScriptedImporter外部に作成済みのAssetへの参照</param>
-        /// <param name="reverseAxis">gltf から unityへの座標変換オプション</param>
-        /// <returns></returns>
-        static ImporterContext Load(string assetPath, Dictionary<AssetImporter.SourceAssetIdentifier, UnityEngine.Object> externalObjectMap, Axises reverseAxis)
-        {
-            //
-            // Parse(parse glb, parser gltf json)
-            //
-            var parser = new GltfParser();
-            parser.ParsePath(assetPath);
-
-            //
-            // Import(create unity objects)
-            //
-            var context = new ImporterContext(parser, null,
-                externalObjectMap.Where(x => x.Value != null).Select(x => (x.Value.name, x.Value)).Concat(
-                EnumerateExists(externalObjectMap, parser, UnityPath.FromUnityPath(assetPath).Parent)));
-            context.InvertAxis = reverseAxis;
-            context.Load();
-            context.ShowMeshes();
-
-            return context;
-        }
-
-        /// <summary>
-        /// UnityObjectをSubAsset化する。
-        /// 
-        /// TODO: SubAsset化されると、ImporterContext から所有権を除去する
-        /// </summary>
-        /// <param name="context"></param>
-        /// <param name="loaded"></param>
-        static void AddSubAssets(AssetImportContext context, ImporterContext loaded)
-        {
-            // Texture
-            foreach (var info in loaded.TextureFactory.Textures)
-            {
-                if (info.IsSubAsset)
-                {
-                    var texture = info.Texture;
-                    context.AddObjectToAsset(texture.name, texture);
-                }
-            }
-
-            // Material
-            foreach (var info in loaded.MaterialFactory.Materials)
-            {
-                if (info.IsSubAsset)
-                {
-                    var material = info.Asset;
-                    context.AddObjectToAsset(material.name, material);
-                }
-            }
-
-            // Mesh
-            foreach (var mesh in loaded.Meshes.Select(x => x.Mesh))
-            {
-                // all mesh is subasset
-                context.AddObjectToAsset(mesh.name, mesh);
-            }
-
-            // Animation
-            foreach (var clip in loaded.AnimationClips)
-            {
-                // all animation is subasset
-                context.AddObjectToAsset(clip.name, clip);
-            }
-
-            // Root GameObject is main object
-            context.AddObjectToAsset(loaded.Root.name, loaded.Root);
-            context.SetMainObject(loaded.Root);
-        }
     }
 }
diff --git a/Assets/UniGLTF/Runtime/UniGLTF/IO/ImporterContext.cs b/Assets/UniGLTF/Runtime/UniGLTF/IO/ImporterContext.cs
index 96427cc08..ddbb1c6d4 100644
--- a/Assets/UniGLTF/Runtime/UniGLTF/IO/ImporterContext.cs
+++ b/Assets/UniGLTF/Runtime/UniGLTF/IO/ImporterContext.cs
@@ -235,14 +235,17 @@ namespace UniGLTF
                 destroy(x);
             }
             AnimationClips.Clear();
+
             foreach (var x in Meshes)
             {
                 destroy(x.Mesh);
             }
             Meshes.Clear();
-            m_materialFactory.Dispose();
-            m_textureFactory.Dispose();
-            destroy(Root);
+
+            // // m_materialFactory.Dispose();
+            // m_textureFactory.Dispose();
+
+            // destroy(Root);
         }
 
         /// <summary>
@@ -256,13 +259,21 @@ namespace UniGLTF
                 add(mesh.Mesh);
             }
             Meshes.Clear();
-            MaterialFactory.TransferOwnership(add);
+
             TextureFactory.TransferOwnership(add);
+            MaterialFactory.TransferOwnership(add);
+
             foreach (var animation in AnimationClips)
             {
                 add(animation);
             }
             AnimationClips.Clear();
+
+            if (Root != null)
+            {
+                add(Root);
+                Root = null;
+            }
         }
 
         /// <summary>
diff --git a/Assets/UniGLTF/Runtime/UniGLTF/IO/MaterialLoader/MaterialFactory.cs b/Assets/UniGLTF/Runtime/UniGLTF/IO/MaterialLoader/MaterialFactory.cs
index d655d20f5..9c683ff02 100644
--- a/Assets/UniGLTF/Runtime/UniGLTF/IO/MaterialLoader/MaterialFactory.cs
+++ b/Assets/UniGLTF/Runtime/UniGLTF/IO/MaterialLoader/MaterialFactory.cs
@@ -75,19 +75,12 @@ namespace UniGLTF
 
         List<MaterialLoadInfo> m_materials = new List<MaterialLoadInfo>();
         public IReadOnlyList<MaterialLoadInfo> Materials => m_materials;
-        public void Dispose()
-        {
-            foreach (var x in ObjectsForSubAsset())
-            {
-                UnityEngine.Object.DestroyImmediate(x, true);
-            }
-        }
 
-        public IEnumerable<UnityEngine.Object> ObjectsForSubAsset()
+        public void Dispose()
         {
             foreach (var x in m_materials)
             {
-                yield return x.Asset;
+                UnityEngine.Object.DestroyImmediate(x.Asset, false);
             }
         }
 
@@ -207,7 +200,10 @@ namespace UniGLTF
         {
             foreach (var x in m_materials)
             {
-                add(x.Asset);
+                if (!x.UseExternal)
+                {
+                    add(x.Asset);
+                }
             }
             m_materials.Clear();
         }
diff --git a/Assets/UniGLTF/Runtime/UniGLTF/IO/TextureLoader/TextureFactory.cs b/Assets/UniGLTF/Runtime/UniGLTF/IO/TextureLoader/TextureFactory.cs
index 341b4e896..7bc4a921d 100644
--- a/Assets/UniGLTF/Runtime/UniGLTF/IO/TextureLoader/TextureFactory.cs
+++ b/Assets/UniGLTF/Runtime/UniGLTF/IO/TextureLoader/TextureFactory.cs
@@ -199,7 +199,7 @@ namespace UniGLTF
             var keys = new List<string>();
             foreach (var x in m_textureCache)
             {
-                if (x.Value.IsUsed)
+                if (x.Value.IsUsed && !x.Value.IsExternal)
                 {
                     keys.Add(x.Key);
                     add(x.Value.Texture);