diff --git a/Assets/UniGLTF/Editor/UniGLTF/Serialization/StringKeyDictionarySerialization.cs b/Assets/UniGLTF/Editor/UniGLTF/Serialization/StringKeyDictionarySerialization.cs
index e09987807..c102d0de2 100644
--- a/Assets/UniGLTF/Editor/UniGLTF/Serialization/StringKeyDictionarySerialization.cs
+++ b/Assets/UniGLTF/Editor/UniGLTF/Serialization/StringKeyDictionarySerialization.cs
@@ -42,7 +42,11 @@ public static $0 $2(ListTreeNode<JsonValue> parsed)
 
         public override string CreateSerializationCondition(string argName, JsonSchemaAttribute t)
         {
-            return $"{argName}!=null&&{argName}.Count>0";
+            // return $"{argName}!=null&&{argName}.Count>0";
+
+            // this check is only /extensions/VRM/materialProperties/*
+            // should export empty dictionary.
+            return $"{argName}!=null";
         }
 
         public override void GenerateSerializer(StreamWriter writer, string callName)
diff --git a/Assets/VRM/Editor/VRMSerializerGenerator.cs b/Assets/VRM/Editor/VRMSerializerGenerator.cs
index 75be56bc4..29e4e9733 100644
--- a/Assets/VRM/Editor/VRMSerializerGenerator.cs
+++ b/Assets/VRM/Editor/VRMSerializerGenerator.cs
@@ -16,7 +16,7 @@ namespace VRM
             get
             {
                 return Path.Combine(UnityEngine.Application.dataPath,
-                "VRM/UniVRM/Scripts/Format/VRMSerializer.g.cs");
+                "VRM/Runtime/Format/VRMSerializer.g.cs");
             }
         }
 
diff --git a/Assets/VRM/Runtime/Format/VRMSerializer.g.cs b/Assets/VRM/Runtime/Format/VRMSerializer.g.cs
index ec49f1e3e..b603ebb48 100644
--- a/Assets/VRM/Runtime/Format/VRMSerializer.g.cs
+++ b/Assets/VRM/Runtime/Format/VRMSerializer.g.cs
@@ -935,27 +935,27 @@ public static void Serialize_vrm_materialProperties_ITEM(JsonFormatter f, glTF_V
         f.Value(value.renderQueue);
     }
 
-    if(value.floatProperties!=null&&value.floatProperties.Count>0){
+    if(value.floatProperties!=null){
         f.Key("floatProperties");                
         Serialize_vrm_materialProperties__floatProperties(f, value.floatProperties);
     }
 
-    if(value.vectorProperties!=null&&value.vectorProperties.Count>0){
+    if(value.vectorProperties!=null){
         f.Key("vectorProperties");                
         Serialize_vrm_materialProperties__vectorProperties(f, value.vectorProperties);
     }
 
-    if(value.textureProperties!=null&&value.textureProperties.Count>0){
+    if(value.textureProperties!=null){
         f.Key("textureProperties");                
         Serialize_vrm_materialProperties__textureProperties(f, value.textureProperties);
     }
 
-    if(value.keywordMap!=null&&value.keywordMap.Count>0){
+    if(value.keywordMap!=null){
         f.Key("keywordMap");                
         Serialize_vrm_materialProperties__keywordMap(f, value.keywordMap);
     }
 
-    if(value.tagMap!=null&&value.tagMap.Count>0){
+    if(value.tagMap!=null){
         f.Key("tagMap");                
         Serialize_vrm_materialProperties__tagMap(f, value.tagMap);
     }