diff --git a/Assets/VRM/UniJSON/Editor/Tests/Json/ValidatorTests.cs b/Assets/VRM/UniJSON/Editor/Tests/Json/ValidatorTests.cs
index b5661c51b..3a071c619 100644
--- a/Assets/VRM/UniJSON/Editor/Tests/Json/ValidatorTests.cs
+++ b/Assets/VRM/UniJSON/Editor/Tests/Json/ValidatorTests.cs
@@ -100,6 +100,12 @@ namespace UniJSON
         {
             var c = new JsonSchemaValidationContext("test");
 
+            {
+                var v = new JsonStringValidator();
+                Assert.Null(v.Validate(c, ""));
+                Assert.Null(v.Validate(c, "a"));
+            }
+
             {
                 var v = new JsonStringValidator();
                 v.MinLength = 1;
diff --git a/Assets/VRM/UniJSON/Scripts/JsonSchemaValidator/JsonStringValidator.cs b/Assets/VRM/UniJSON/Scripts/JsonSchemaValidator/JsonStringValidator.cs
index fb55cedb5..5b5f86d07 100644
--- a/Assets/VRM/UniJSON/Scripts/JsonSchemaValidator/JsonStringValidator.cs
+++ b/Assets/VRM/UniJSON/Scripts/JsonSchemaValidator/JsonStringValidator.cs
@@ -111,10 +111,6 @@ namespace UniJSON
             }
 
             var value = o as string;
-            if (value.All(x => Char.IsWhiteSpace(x)))
-            {
-                return new JsonSchemaValidationException(c, "whitespace");
-            }
 
             if (MinLength.HasValue && value.Length < MinLength)
             {