diff --git a/CHANGELOG.md b/CHANGELOG.md
index fdbbb2c..bb38e3a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,12 @@ All notable changes to this project will be documented in this file.
 
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
+## [Unreleased]
+
+### Fixed
+
+* Fix return correct error values for out-of-index arguments in cubismjson.
+
 
 ## [4-r.3] - 2021-06-10
 
diff --git a/src/utils/cubismjson.ts b/src/utils/cubismjson.ts
index 93a41a3..d8097a0 100644
--- a/src/utils/cubismjson.ts
+++ b/src/utils/cubismjson.ts
@@ -74,7 +74,7 @@ export abstract class Value {
   /**
    * 要素をコンテナで返す(array)
    */
-  public getVector(defaultValue?: csmVector<Value>): csmVector<Value> {
+  public getVector(defaultValue = new csmVector<Value>()): csmVector<Value> {
     return defaultValue;
   }
 
@@ -192,10 +192,8 @@ export abstract class Value {
   public static staticInitializeNotForClientCall(): void {
     JsonBoolean.trueValue = new JsonBoolean(true);
     JsonBoolean.falseValue = new JsonBoolean(false);
-
-    JsonError.errorValue = new JsonError('ERROR', true);
-    this.nullValue = new JsonNullvalue();
-
+    Value.errorValue = new JsonError('ERROR', true);
+    Value.nullValue = new JsonNullvalue();
     Value.s_dummyKeys = new csmVector<string>();
   }
 
@@ -205,13 +203,7 @@ export abstract class Value {
   public static staticReleaseNotForClientCall(): void {
     JsonBoolean.trueValue = null;
     JsonBoolean.falseValue = null;
-    JsonError.errorValue = null;
-    Value.nullValue = null;
-    Value.s_dummyKeys = null;
-
-    JsonBoolean.trueValue = null;
-    JsonBoolean.falseValue = null;
-    JsonError.errorValue = null;
+    Value.errorValue = null;
     Value.nullValue = null;
     Value.s_dummyKeys = null;
   }
@@ -970,6 +962,14 @@ export class JsonNullvalue extends Value {
     return true;
   }
 
+  /**
+   * Valueにエラー値をセットする
+   */
+  public setErrorNotForClientCall(s: string): Value {
+    this._stringBuffer = s;
+    return JsonError.nullValue;
+  }
+
   /**
    * コンストラクタ
    */