diff --git a/Assets/VRM/UniVRM/Editor/Tests/UniVRMSerializeTests.cs b/Assets/VRM/UniVRM/Editor/Tests/UniVRMSerializeTests.cs
index deb4fed5e..b3d3362d9 100644
--- a/Assets/VRM/UniVRM/Editor/Tests/UniVRMSerializeTests.cs
+++ b/Assets/VRM/UniVRM/Editor/Tests/UniVRMSerializeTests.cs
@@ -237,10 +237,17 @@ namespace VRM
         [Test]
         public void MetaTest()
         {
-            var model = new glTF_VRM_Meta();
+            var model = new glTF_VRM_Meta()
+            {
+                allowedUserName = "OnlyAuthor",
+                violentUssageName = "Disallow",
+                sexualUssageName = "Disallow",
+                commercialUssageName = "Disallow",
+                licenseName = "CC0",
+            };
 
             var json = model.ToJson();
-            Assert.AreEqual(@"{""texture"":-1}", json);
+            Assert.AreEqual(@"{""texture"":-1,""allowedUserName"":""OnlyAuthor"",""violentUssageName"":""Disallow"",""sexualUssageName"":""Disallow"",""commercialUssageName"":""Disallow"",""licenseName"":""CC0""}", json);
             Debug.Log(json);
 
             var c = new JsonSchemaValidationContext("")
@@ -249,7 +256,224 @@ namespace VRM
             };
             var json2 = JsonSchema.FromType<glTF_VRM_Meta>().Serialize(model, c);
             // NOTE: New serializer outputs values which will not be used...
-            Assert.AreEqual(@"{}",json2);
+            Assert.AreEqual(@"{""allowedUserName"":""OnlyAuthor"",""violentUssageName"":""Disallow"",""sexualUssageName"":""Disallow"",""commercialUssageName"":""Disallow"",""licenseName"":""CC0""}",json2);
+        }
+
+        [Test]
+        public void MetaTestError()
+        {
+            {
+                var model = new glTF_VRM_Meta();
+
+                var c = new JsonSchemaValidationContext("")
+                {
+                    EnableDiagnosisForNotRequiredFields = true,
+                };
+                var ex = Assert.Throws<JsonSchemaValidationException>(
+                    () => JsonSchema.FromType<glTF_VRM_Meta>().Serialize(model, c)
+                );
+                Assert.AreEqual("[allowedUserName.String] null", ex.Message);
+            }
+
+            {
+                var model = new glTF_VRM_Meta()
+                {
+                    allowedUserName = "OnlyAuthor",
+                    violentUssageName = "Disallow",
+                    sexualUssageName = "Disallow",
+                    commercialUssageName = "Disallow",
+                    //licenseName = "CC0",
+                };
+
+                var c = new JsonSchemaValidationContext("")
+                {
+                    EnableDiagnosisForNotRequiredFields = true,
+                };
+                var ex = Assert.Throws<JsonSchemaValidationException>(
+                    () => JsonSchema.FromType<glTF_VRM_Meta>().Serialize(model, c)
+                );
+                Assert.AreEqual("[licenseName.String] null", ex.Message);
+            }
+
+            {
+                var model = new glTF_VRM_Meta()
+                {
+                    allowedUserName = "OnlyAuthor",
+                    violentUssageName = "Disallow",
+                    sexualUssageName = "Disallow",
+                    commercialUssageName = "Disallow",
+                    licenseName = "_INVALID_SOME_THING_",
+                };
+
+                var c = new JsonSchemaValidationContext("")
+                {
+                    EnableDiagnosisForNotRequiredFields = true,
+                };
+                var ex = Assert.Throws<JsonSchemaValidationException>(
+                    () => JsonSchema.FromType<glTF_VRM_Meta>().Serialize(model, c)
+                );
+                Assert.AreEqual("[licenseName.String] _INVALID_SOME_THING_ is not valid enum", ex.Message);
+            }
+
+            {
+                var model = new glTF_VRM_Meta()
+                {
+                    // allowedUserName = "OnlyAuthor",
+                    violentUssageName = "Disallow",
+                    sexualUssageName = "Disallow",
+                    commercialUssageName = "Disallow",
+                    licenseName = "CC0",
+                };
+
+                var c = new JsonSchemaValidationContext("")
+                {
+                    EnableDiagnosisForNotRequiredFields = true,
+                };
+                var ex = Assert.Throws<JsonSchemaValidationException>(
+                    () => JsonSchema.FromType<glTF_VRM_Meta>().Serialize(model, c)
+                );
+                Assert.AreEqual("[allowedUserName.String] null", ex.Message);
+            }
+
+            {
+                var model = new glTF_VRM_Meta()
+                {
+                    allowedUserName = "_INVALID_SOME_THING_",
+                    violentUssageName = "Disallow",
+                    sexualUssageName = "Disallow",
+                    commercialUssageName = "Disallow",
+                    licenseName = "CC0",
+                };
+
+                var c = new JsonSchemaValidationContext("")
+                {
+                    EnableDiagnosisForNotRequiredFields = true,
+                };
+                var ex = Assert.Throws<JsonSchemaValidationException>(
+                    () => JsonSchema.FromType<glTF_VRM_Meta>().Serialize(model, c)
+                );
+                Assert.AreEqual("[allowedUserName.String] _INVALID_SOME_THING_ is not valid enum", ex.Message);
+            }
+
+            {
+                var model = new glTF_VRM_Meta()
+                {
+                    allowedUserName = "OnlyAuthor",
+                    //violentUssageName = "Disallow",
+                    sexualUssageName = "Disallow",
+                    commercialUssageName = "Disallow",
+                    licenseName = "CC0",
+                };
+
+                var c = new JsonSchemaValidationContext("")
+                {
+                    EnableDiagnosisForNotRequiredFields = true,
+                };
+                var ex = Assert.Throws<JsonSchemaValidationException>(
+                    () => JsonSchema.FromType<glTF_VRM_Meta>().Serialize(model, c)
+                );
+                Assert.AreEqual("[violentUssageName.String] null", ex.Message);
+            }
+
+            {
+                var model = new glTF_VRM_Meta()
+                {
+                    allowedUserName = "OnlyAuthor",
+                    violentUssageName = "_INVALID_SOME_THING_",
+                    sexualUssageName = "Disallow",
+                    commercialUssageName = "Disallow",
+                    licenseName = "CC0",
+                };
+
+                var c = new JsonSchemaValidationContext("")
+                {
+                    EnableDiagnosisForNotRequiredFields = true,
+                };
+                var ex = Assert.Throws<JsonSchemaValidationException>(
+                    () => JsonSchema.FromType<glTF_VRM_Meta>().Serialize(model, c)
+                );
+                Assert.AreEqual("[violentUssageName.String] _INVALID_SOME_THING_ is not valid enum", ex.Message);
+            }
+
+            {
+                var model = new glTF_VRM_Meta()
+                {
+                    allowedUserName = "OnlyAuthor",
+                    violentUssageName = "Disallow",
+                    //sexualUssageName = "Disallow",
+                    commercialUssageName = "Disallow",
+                    licenseName = "CC0",
+                };
+
+                var c = new JsonSchemaValidationContext("")
+                {
+                    EnableDiagnosisForNotRequiredFields = true,
+                };
+                var ex = Assert.Throws<JsonSchemaValidationException>(
+                    () => JsonSchema.FromType<glTF_VRM_Meta>().Serialize(model, c)
+                );
+                Assert.AreEqual("[sexualUssageName.String] null", ex.Message);
+            }
+
+            {
+                var model = new glTF_VRM_Meta()
+                {
+                    allowedUserName = "OnlyAuthor",
+                    violentUssageName = "Disallow",
+                    sexualUssageName = "_INVALID_SOME_THING_",
+                    commercialUssageName = "Disallow",
+                    licenseName = "CC0",
+                };
+
+                var c = new JsonSchemaValidationContext("")
+                {
+                    EnableDiagnosisForNotRequiredFields = true,
+                };
+                var ex = Assert.Throws<JsonSchemaValidationException>(
+                    () => JsonSchema.FromType<glTF_VRM_Meta>().Serialize(model, c)
+                );
+                Assert.AreEqual("[sexualUssageName.String] _INVALID_SOME_THING_ is not valid enum", ex.Message);
+            }
+
+            {
+                var model = new glTF_VRM_Meta()
+                {
+                    allowedUserName = "OnlyAuthor",
+                    violentUssageName = "Disallow",
+                    sexualUssageName = "Disallow",
+                    //commercialUssageName = "Disallow",
+                    licenseName = "CC0",
+                };
+
+                var c = new JsonSchemaValidationContext("")
+                {
+                    EnableDiagnosisForNotRequiredFields = true,
+                };
+                var ex = Assert.Throws<JsonSchemaValidationException>(
+                    () => JsonSchema.FromType<glTF_VRM_Meta>().Serialize(model, c)
+                );
+                Assert.AreEqual("[commercialUssageName.String] null", ex.Message);
+            }
+
+            {
+                var model = new glTF_VRM_Meta()
+                {
+                    allowedUserName = "OnlyAuthor",
+                    violentUssageName = "Disallow",
+                    sexualUssageName = "Disallow",
+                    commercialUssageName = "_INVALID_SOME_THING_",
+                    licenseName = "CC0",
+                };
+
+                var c = new JsonSchemaValidationContext("")
+                {
+                    EnableDiagnosisForNotRequiredFields = true,
+                };
+                var ex = Assert.Throws<JsonSchemaValidationException>(
+                    () => JsonSchema.FromType<glTF_VRM_Meta>().Serialize(model, c)
+                );
+                Assert.AreEqual("[commercialUssageName.String] _INVALID_SOME_THING_ is not valid enum", ex.Message);
+            }
         }
 
         // TODO: Move to another suitable location
diff --git a/Assets/VRM/UniVRM/Scripts/Format/glTF_VRM_Meta.cs b/Assets/VRM/UniVRM/Scripts/Format/glTF_VRM_Meta.cs
index 7d8dfb0db..ceceead64 100644
--- a/Assets/VRM/UniVRM/Scripts/Format/glTF_VRM_Meta.cs
+++ b/Assets/VRM/UniVRM/Scripts/Format/glTF_VRM_Meta.cs
@@ -59,7 +59,7 @@ namespace VRM
         public int texture = -1;
 
         #region Ussage Permission
-        [JsonSchema(Description = "A person who can perform with this avatar ", EnumValues = new object[] {
+        [JsonSchema(Required = true, Description = "A person who can perform with this avatar ", EnumValues = new object[] {
             "OnlyAuthor",
             "ExplicitlyLicensedPerson",
             "Everyone",
@@ -77,7 +77,7 @@ namespace VRM
             }
         }
 
-        [JsonSchema(Description = "Permission to perform violent acts with this avatar", EnumValues = new object[]
+        [JsonSchema(Required = true, Description = "Permission to perform violent acts with this avatar", EnumValues = new object[]
         {
         "Disallow",
         "Allow",
@@ -89,7 +89,7 @@ namespace VRM
             set { violentUssageName = value.ToString(); }
         }
 
-        [JsonSchema(Description = "Permission to perform sexual acts with this avatar", EnumValues = new object[]
+        [JsonSchema(Required = true, Description = "Permission to perform sexual acts with this avatar", EnumValues = new object[]
         {
         "Disallow",
         "Allow",
@@ -101,7 +101,7 @@ namespace VRM
             set { sexualUssageName = value.ToString(); }
         }
 
-        [JsonSchema(Description = "For commercial use", EnumValues = new object[]
+        [JsonSchema(Required = true, Description = "For commercial use", EnumValues = new object[]
         {
         "Disallow",
         "Allow",
@@ -118,7 +118,7 @@ namespace VRM
         #endregion
 
         #region Distribution License
-        [JsonSchema(Description = "License type", EnumValues = new object[]
+        [JsonSchema(Required = true, Description = "License type", EnumValues = new object[]
         {
             "Redistribution_Prohibited",
             "CC0",