diff --git a/Assets/VRM10/Runtime/IO/Vrm10Importer.cs b/Assets/VRM10/Runtime/IO/Vrm10Importer.cs
index 0d6a2b495..5b5cd31c3 100644
--- a/Assets/VRM10/Runtime/IO/Vrm10Importer.cs
+++ b/Assets/VRM10/Runtime/IO/Vrm10Importer.cs
@@ -15,11 +15,15 @@ namespace UniVRM10
     /// </summary>
     public class Vrm10Importer : UniGLTF.ImporterContext
     {
-        VrmLib.Model m_model;
+        private readonly Vrm10Data m_vrm;
+        /// VrmLib.Model の オブジェクトと UnityEngine.Object のマッピングを記録する
+        private readonly ModelMap m_map = new ModelMap();
 
-        readonly Vrm10Data m_vrm;
-
-        IReadOnlyDictionary<SubAssetKey, UnityEngine.Object> m_externalMap;
+        private VrmLib.Model m_model;
+        private IReadOnlyDictionary<SubAssetKey, UnityEngine.Object> m_externalMap;
+        private Avatar m_humanoid;
+        private VRM10Object m_vrmObject;
+        private List<(ExpressionPreset Preset, VRM10Expression Clip)> m_expressions = new List<(ExpressionPreset, VRM10Expression)>();
 
         public Vrm10Importer(
             Vrm10Data vrm,
@@ -44,18 +48,6 @@ namespace UniVRM10
             }
         }
 
-        public class ModelMap
-        {
-            public readonly Dictionary<VrmLib.Node, GameObject> Nodes = new Dictionary<VrmLib.Node, GameObject>();
-            public readonly Dictionary<VrmLib.MeshGroup, UnityEngine.Mesh> Meshes = new Dictionary<VrmLib.MeshGroup, UnityEngine.Mesh>();
-        }
-
-        /// <summary>
-        /// VrmLib.Model の オブジェクトと UnityEngine.Object のマッピングを記録する
-        /// </summary>
-        /// <returns></returns>
-        readonly ModelMap m_map = new ModelMap();
-
         static void AssignHumanoid(List<VrmLib.Node> nodes, UniGLTF.Extensions.VRMC_vrm.HumanBone humanBone, VrmLib.HumanoidBones key)
         {
             if (nodes == null)
@@ -237,10 +229,6 @@ namespace UniVRM10
             }
         }
 
-        UnityEngine.Avatar m_humanoid;
-        VRM10Object m_vrmObject;
-        List<(ExpressionPreset Preset, VRM10Expression Clip)> m_expressions = new List<(ExpressionPreset, VRM10Expression)>();
-
         protected override async Task OnLoadHierarchy(IAwaitCaller awaitCaller, Func<string, IDisposable> MeasureTime)
         {
             Root.name = "VRM1";
@@ -847,5 +835,11 @@ namespace UniVRM10
 
             base.Dispose();
         }
+
+        public sealed class ModelMap
+        {
+            public readonly Dictionary<VrmLib.Node, GameObject> Nodes = new Dictionary<VrmLib.Node, GameObject>();
+            public readonly Dictionary<VrmLib.MeshGroup, UnityEngine.Mesh> Meshes = new Dictionary<VrmLib.MeshGroup, UnityEngine.Mesh>();
+        }
     }
 }
\ No newline at end of file