diff --git a/Assets/UniGLTF/Editor/UniGLTF/ExportDialog/MeshExportValidator.cs b/Assets/UniGLTF/Editor/UniGLTF/ExportDialog/MeshExportValidator.cs
index becf276b1..0f162ceb9 100644
--- a/Assets/UniGLTF/Editor/UniGLTF/ExportDialog/MeshExportValidator.cs
+++ b/Assets/UniGLTF/Editor/UniGLTF/ExportDialog/MeshExportValidator.cs
@@ -193,7 +193,8 @@ namespace UniGLTF
 
         public enum Messages
         {
-            DIFFERENT_MATERIAL_COUNT,
+            MATERIALS_LESS_THAN_SUBMESH_COUNT,
+            MATERIALS_GREATER_THAN_SUBMESH_COUNT,
             MATERIALS_CONTAINS_NULL,
             UNKNOWN_SHADER,
         }
@@ -205,18 +206,22 @@ namespace UniGLTF
                 // invalid materials.len
                 if (info.Renderer.sharedMaterials.Length < info.Mesh.subMeshCount)
                 {
-                    // すべての submesh に material が割り当てられていない
-                    yield return Validation.Error(Messages.DIFFERENT_MATERIAL_COUNT.Msg());
+                    // submesh より material の方が少ない
+                    yield return Validation.Error(Messages.MATERIALS_LESS_THAN_SUBMESH_COUNT.Msg());
                 }
-                else if (info.Renderer.sharedMaterials.Length > info.Mesh.subMeshCount)
+                else
                 {
-                    // 未使用の material がある
-                    yield return Validation.Warning(Messages.DIFFERENT_MATERIAL_COUNT.Msg());
-                }
-                else if (info.Renderer.sharedMaterials.Any(x => x == null))
-                {
-                    // material に null が含まれる(unity で magenta になっているはず)
-                    yield return Validation.Error($"{info.Renderer}: {Messages.MATERIALS_CONTAINS_NULL.Msg()}");
+                    if (info.Renderer.sharedMaterials.Length > info.Mesh.subMeshCount)
+                    {
+                        // submesh より material の方が多い
+                        yield return Validation.Warning(Messages.MATERIALS_GREATER_THAN_SUBMESH_COUNT.Msg());
+                    }
+
+                    if (info.Renderer.sharedMaterials.Take(info.Mesh.subMeshCount).Any(x => x == null))
+                    {
+                        // material に null が含まれる(unity で magenta になっているはず)
+                        yield return Validation.Error($"{info.Renderer}: {Messages.MATERIALS_CONTAINS_NULL.Msg()}");
+                    }
                 }
             }
 
diff --git a/Assets/UniGLTF/Tests/UniGLTF/MeshExportValidatorTests.cs b/Assets/UniGLTF/Tests/UniGLTF/MeshExportValidatorTests.cs
index 72cd34ad3..a2d8058fa 100644
--- a/Assets/UniGLTF/Tests/UniGLTF/MeshExportValidatorTests.cs
+++ b/Assets/UniGLTF/Tests/UniGLTF/MeshExportValidatorTests.cs
@@ -6,20 +6,26 @@ namespace UniGLTF
 {
     public class MeshExportValidatorTests
     {
+        static GameObject CreateTestObject(Material[] materials)
+        {
+            var root = new GameObject("root");
+            var cube = GameObject.CreatePrimitive(PrimitiveType.Cube);
+            cube.transform.SetParent(root.transform);
+
+            var renderer = cube.GetComponent<Renderer>();
+            renderer.sharedMaterials = materials;
+            return root;
+        }
+
         [Test]
         public void NoMaterialTest()
         {
             var validator = ScriptableObject.CreateInstance<MeshExportValidator>();
-            var root = new GameObject("root");
+            // 0 material
+            var root = CreateTestObject(new Material[0]);
 
             try
             {
-                var cube = GameObject.CreatePrimitive(PrimitiveType.Cube);
-                cube.transform.SetParent(root.transform);
-
-                var renderer = cube.GetComponent<Renderer>();
-                renderer.sharedMaterials = new Material[0];
-
                 validator.SetRoot(root, MeshExportSettings.Default);
                 var vs = validator.Validate(root);
                 Assert.False(vs.All(x => x.CanExport));
@@ -35,16 +41,11 @@ namespace UniGLTF
         public void NullMaterialTest()
         {
             var validator = ScriptableObject.CreateInstance<MeshExportValidator>();
-            var root = new GameObject("root");
+            // null を含む
+            var root = CreateTestObject(new Material[] { null });
 
             try
             {
-                var cube = GameObject.CreatePrimitive(PrimitiveType.Cube);
-                cube.transform.SetParent(root.transform);
-
-                var renderer = cube.GetComponent<Renderer>();
-                renderer.sharedMaterials = new Material[] { null };
-
                 validator.SetRoot(root, MeshExportSettings.Default);
                 var vs = validator.Validate(root);
                 Assert.False(vs.All(x => x.CanExport));
@@ -60,16 +61,11 @@ namespace UniGLTF
         public void NullMaterialsTest()
         {
             var validator = ScriptableObject.CreateInstance<MeshExportValidator>();
-            var root = new GameObject("root");
+            // null を含むかつ submeshCount より多い
+            var root = CreateTestObject(new Material[] { null, null });
 
             try
             {
-                var cube = GameObject.CreatePrimitive(PrimitiveType.Cube);
-                cube.transform.SetParent(root.transform);
-
-                var renderer = cube.GetComponent<Renderer>();
-                renderer.sharedMaterials = new Material[] { null, null };
-
                 validator.SetRoot(root, MeshExportSettings.Default);
                 var vs = validator.Validate(root);
                 Assert.False(vs.All(x => x.CanExport));