diff --git a/Assets/VRM10/Runtime/Migration/Materials/MigrationLegacyUnlitMaterial.cs b/Assets/VRM10/Runtime/Migration/Materials/MigrationLegacyUnlitMaterial.cs
index 58bb79d86..dd07b5cd9 100644
--- a/Assets/VRM10/Runtime/Migration/Materials/MigrationLegacyUnlitMaterial.cs
+++ b/Assets/VRM10/Runtime/Migration/Materials/MigrationLegacyUnlitMaterial.cs
@@ -10,7 +10,7 @@ namespace UniVRM10
     /// 過去の UniVRM において、KHR_materials_unlit 拡張を使わず、VRM 拡張を用いて Unlit を表現していた Material をマイグレーションする。
     /// KHR_materials_unlit を用いてマイグレーションする.
     /// </summary>
-    public static class MigrationLegacyUnlitMaterial
+    internal static class MigrationLegacyUnlitMaterial
     {
         public static bool Migrate(glTF gltf, IReadOnlyList<JsonNode> vrm0XMaterials)
         {
diff --git a/Assets/VRM10/Runtime/Migration/Materials/MigrationMToonMaterial.cs b/Assets/VRM10/Runtime/Migration/Materials/MigrationMToonMaterial.cs
index 673ef5dc8..34a19099d 100644
--- a/Assets/VRM10/Runtime/Migration/Materials/MigrationMToonMaterial.cs
+++ b/Assets/VRM10/Runtime/Migration/Materials/MigrationMToonMaterial.cs
@@ -12,7 +12,7 @@ using RenderMode = MToon.RenderMode;
 
 namespace UniVRM10
 {
-    public static class MigrationMToonMaterial
+    internal static class MigrationMToonMaterial
     {
         private const string MigrationMToon10SpecVersion = "1.0-draft";
 
diff --git a/Assets/VRM10/Runtime/Migration/Materials/MigrationUnlitTransparentZWriteMaterial.cs b/Assets/VRM10/Runtime/Migration/Materials/MigrationUnlitTransparentZWriteMaterial.cs
index 06c965078..6339a17e6 100644
--- a/Assets/VRM10/Runtime/Migration/Materials/MigrationUnlitTransparentZWriteMaterial.cs
+++ b/Assets/VRM10/Runtime/Migration/Materials/MigrationUnlitTransparentZWriteMaterial.cs
@@ -11,7 +11,7 @@ namespace UniVRM10
     /// 過去の UniVRM の "VRM/UnlitTransparentZWrite" シェーダをマイグレーションする.
     /// 他の Unlit シェーダと違い、VRMC_materials_mtoon を用いてマイグレーションする.
     /// </summary>
-    public static class MigrationUnlitTransparentZWriteMaterial
+    internal static class MigrationUnlitTransparentZWriteMaterial
     {
         private const string MigrationMToon10SpecVersion = "1.0-draft"; // NOTE: vrm-1.0 spec
         private const int MaxRenderQueueOffset = 9; // NOTE: vrm-1.0 spec