diff --git a/Assets/VRM/Runtime/IO/VRMMToonMaterialImporter.cs b/Assets/VRM/Runtime/IO/VRMMToonMaterialImporter.cs
index 4ab6d48a32..7a5b2b0418 100644
--- a/Assets/VRM/Runtime/IO/VRMMToonMaterialImporter.cs
+++ b/Assets/VRM/Runtime/IO/VRMMToonMaterialImporter.cs
@@ -8,6 +8,17 @@ public static class VRMMToonMaterialImporter
     {
         public static bool TryCreateParam(GltfData data, glTF_VRM_extensions vrm, int materialIdx, out MaterialDescriptor matDesc)
         {
+            if (vrm?.materialProperties == null || vrm.materialProperties.Count == 0)
+            {
+                matDesc = default;
+                return false;
+            }
+            if (materialIdx < 0 || materialIdx >= vrm.materialProperties.Count)
+            {
+                matDesc = default;
+                return false;
+            }
+
             var vrmMaterial = vrm.materialProperties[materialIdx];
             if (vrmMaterial.shader == VRM.glTF_VRM_Material.VRM_USE_GLTFSHADER)
             {
@@ -42,7 +53,7 @@ public static bool TryCreateParam(GltfData data, glTF_VRM_extensions vrm, int ma
 
             foreach (var kv in vrmMaterial.textureProperties)
             {
-                if (VRMMToonTextureImporter.TryGetTextureFromMaterialProperty(data, vrm, materialIdx, kv.Key, out var texture))
+                if (VRMMToonTextureImporter.TryGetTextureFromMaterialProperty(data, vrmMaterial, kv.Key, out var texture))
                 {
                     matDesc.TextureSlots.Add(kv.Key, texture.Item2);
                 }
diff --git a/Assets/VRM/Runtime/IO/VRMMToonTextureImporter.cs b/Assets/VRM/Runtime/IO/VRMMToonTextureImporter.cs
index 596999e89a..de8dd36228 100644
--- a/Assets/VRM/Runtime/IO/VRMMToonTextureImporter.cs
+++ b/Assets/VRM/Runtime/IO/VRMMToonTextureImporter.cs
@@ -12,21 +12,19 @@ public static class VRMMToonTextureImporter
             var vrmMaterial = vrm.materialProperties[materialIdx];
             foreach (var kv in vrmMaterial.textureProperties)
             {
-                if (TryGetTextureFromMaterialProperty(data, vrm, materialIdx, kv.Key, out var texture))
+                if (TryGetTextureFromMaterialProperty(data, vrmMaterial, kv.Key, out var texture))
                 {
                     yield return texture;
                 }
             }
         }
-
-        public static bool TryGetTextureFromMaterialProperty(GltfData data, glTF_VRM_extensions vrm, int materialIdx, string textureKey, out (SubAssetKey, TextureDescriptor) texture)
+        public static bool TryGetTextureFromMaterialProperty(GltfData data, glTF_VRM_Material vrmMaterial, string textureKey, out (SubAssetKey, TextureDescriptor) texture)
         {
-            var vrmMaterial = vrm.materialProperties[materialIdx];
             // 任意の shader の import を許容する
             if (/*vrmMaterial.shader == MToon.Utils.ShaderName &&*/ vrmMaterial.textureProperties.TryGetValue(textureKey, out var textureIdx))
             {
                 var (offset, scale) = (new Vector2(0, 0), new Vector2(1, 1));
-                if (TryGetTextureOffsetAndScale(vrm, materialIdx, textureKey, out var os))
+                if (TryGetTextureOffsetAndScale(vrmMaterial, textureKey, out var os))
                 {
                     offset = os.offset;
                     scale = os.scale;
@@ -48,10 +46,8 @@ public static bool TryGetTextureFromMaterialProperty(GltfData data, glTF_VRM_ext
             return false;
         }
 
-        public static bool TryGetTextureOffsetAndScale(glTF_VRM_extensions vrm, int materialIdx, string unityTextureKey, out (Vector2 offset, Vector2 scale) os)
+        public static bool TryGetTextureOffsetAndScale(glTF_VRM_Material vrmMaterial, string unityTextureKey, out (Vector2 offset, Vector2 scale) os)
         {
-            var vrmMaterial = vrm.materialProperties[materialIdx];
-
             if (vrmMaterial.vectorProperties.TryGetValue(unityTextureKey, out var vector))
             {
                 os = (new Vector2(vector[0], vector[1]), new Vector2(vector[2], vector[3]));