diff --git a/README.md b/README.md
index 74d67aa..a78f75c 100644
--- a/README.md
+++ b/README.md
@@ -50,19 +50,25 @@ const parsedParameters = parameters.parse({
 //=> { TOKEN: 'xxxx', FIREBASE_CONFIG: { apiKey: 'xxxx' } }
 ```
 
-### API
+## API
 
 see `test/index.spec.ts`.
 
-```ts
-import { createTypedParameters } from 'construct-typed-parameters';
+### createTypedParameters
 
-// type ParameterValidate<T> = (value: T) => string | string[] | null;
+```ts
+import {
+  createTypedParameters,
+  TypedParametersConstruct,
+} from 'construct-typed-parameters';
 
-const parameters = createTypedParameters(pt => ({
+const parameters: TypedParametersConstruct<T> = createTypedParameters(pt => ({
   stringValue: pt.String({
+    // required: boolean
     required: true,
+    // defaultValue?: T1
     defaultValue: 'xxxx',
+    // validate?: (value: T1) => string | string[] | null;
     validate: v => (v.includes('x') ? null : 'the value must contain x'),
   }),
   unionStringValue: pt.UnionString<'v1' | 'v2'>({
@@ -99,6 +105,28 @@ const parameters = createTypedParameters(pt => ({
 }));
 ```
 
+### TypedParametersConstruct#parse
+
+```ts
+const parameters: TypedParametersConstruct<T> = createTypedParameters(pt => ({ ... }));
+
+parameters.parse(
+  stringifiedParameters: Partial<StringifiedParameters<T>>,
+  shouldValidate = true
+) : ParsedParameters<T>
+```
+
+### TypedParametersConstruct#stringify
+
+```ts
+const parameters: TypedParametersConstruct<T> = createTypedParameters(pt => ({ ... }));
+
+parameters.stringify(
+  parsedParameters: Partial<ParsedParameters<T>>,
+  shouldValidate = true
+) : StringifiedParameters<T>
+```
+
 [build-img]: https://github.com/masahirompp/construct-typed-parameters/actions/workflows/release.yml/badge.svg
 [build-url]: https://github.com/masahirompp/construct-typed-parameters/actions/workflows/release.yml
 [downloads-img]: https://img.shields.io/npm/dt/construct-typed-parameters
diff --git a/src/index.ts b/src/index.ts
index c329af5..950228a 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -136,14 +136,17 @@ const ParameterType = {
 class TypedParameters<T extends Record<string, ParameterConstruct<any>>> {
   constructor(private parametersConstruct: T) {}
 
-  parse(serializedParameters: Partial<StringifiedParameters<T>>) {
+  parse(
+    stringifiedParameters: Partial<StringifiedParameters<T>>,
+    shouldValidate = true
+  ) {
     const requiredErrorParameters: string[] = [];
     const validationErrorParameterMap: Record<string, string[]> = {};
     const result = Object.entries(this.parametersConstruct).reduce<
       ParsedParameters<T>
     >((payload, [parameterName, construct]) => {
       const value = (() => {
-        const serialized = serializedParameters[parameterName];
+        const serialized = stringifiedParameters[parameterName];
         const parsedValue =
           typeof serialized === 'string'
             ? construct.parse(serialized)
@@ -156,13 +159,17 @@ class TypedParameters<T extends Record<string, ParameterConstruct<any>>> {
           // eslint-disable-next-line @typescript-eslint/no-unsafe-return
           return construct.defaultValue;
         }
-        if (construct.required) {
+        if (shouldValidate && construct.required) {
           requiredErrorParameters.push(parameterName);
         }
         return undefined;
       })();
 
-      if (value != null && typeof construct.validate === 'function') {
+      if (
+        shouldValidate &&
+        value != null &&
+        typeof construct.validate === 'function'
+      ) {
         const validationError = construct.validate(value);
         if (validationError) {
           if (Array.isArray(validationError)) {
@@ -188,23 +195,30 @@ class TypedParameters<T extends Record<string, ParameterConstruct<any>>> {
       throw new ParameterError(
         requiredErrorParameters,
         validationErrorParameterMap,
-        serializedParameters,
+        stringifiedParameters,
         result
       );
     }
     return result;
   }
 
-  stringify(parameters: Partial<ParsedParameters<T>>) {
+  stringify(
+    parsedParameters: Partial<ParsedParameters<T>>,
+    shouldValidate = true
+  ) {
     const requiredErrorParameters: string[] = [];
     const validationErrorParameterMap: Record<string, string[]> = {};
     const result = Object.entries(this.parametersConstruct).reduce<
       StringifiedParameters<T>
     >((payload, [parameterName, construct]) => {
       const serialized = (() => {
-        const value = parameters[parameterName];
+        const value = parsedParameters[parameterName];
 
-        if (value != null && typeof construct.validate === 'function') {
+        if (
+          shouldValidate &&
+          value != null &&
+          typeof construct.validate === 'function'
+        ) {
           const validationError = construct.validate(value);
           if (validationError) {
             if (Array.isArray(validationError)) {
@@ -230,7 +244,7 @@ class TypedParameters<T extends Record<string, ParameterConstruct<any>>> {
             return serializedDefaultValue;
           }
         }
-        if (construct.required) {
+        if (shouldValidate && construct.required) {
           requiredErrorParameters.push(parameterName);
         }
         return undefined;
@@ -250,7 +264,7 @@ class TypedParameters<T extends Record<string, ParameterConstruct<any>>> {
         requiredErrorParameters,
         validationErrorParameterMap,
         result,
-        parameters
+        parsedParameters
       );
     }
     return result;
diff --git a/test/index.spec.ts b/test/index.spec.ts
index b766357..b45662d 100644
--- a/test/index.spec.ts
+++ b/test/index.spec.ts
@@ -41,6 +41,10 @@ describe('index', () => {
       );
     });
 
+    it('parse required error but should not validate', () => {
+      expect(parameters.parse({}, false)).toEqual({});
+    });
+
     it('stringify', () => {
       expect(
         parameters.stringify({
@@ -69,6 +73,10 @@ describe('index', () => {
         'stringValue is required, unionStringValue is required, numberValue is required, unionNumberValue is required, booleanValue is required, jsonValue is required, arrayValue is required.'
       );
     });
+
+    it('stringify required error but should not validate', () => {
+      expect(parameters.stringify({}, false)).toEqual({});
+    });
   });
 
   describe('all required with defaultValue.', () => {
@@ -401,6 +409,33 @@ describe('index', () => {
       );
     });
 
+    it('parse validation error but should not validate', () => {
+      expect(
+        parameters.parse(
+          {
+            stringValue: 'yyyy',
+            unionStringValue: 'v3',
+            numberValue: '0',
+            unionNumberValue: '-1',
+            booleanValue: 'false',
+            jsonValue: '{"apiKey":""}',
+            arrayValue: '[]',
+          },
+          false
+        )
+      ).toEqual({
+        arrayValue: [],
+        booleanValue: false,
+        jsonValue: {
+          apiKey: '',
+        },
+        numberValue: 0,
+        stringValue: 'yyyy',
+        unionNumberValue: -1,
+        unionStringValue: 'v3',
+      });
+    });
+
     it('parse required error and validation error', () => {
       expect(() =>
         parameters.parse({
@@ -414,6 +449,25 @@ describe('index', () => {
       );
     });
 
+    it('parse required error and validation error, but should not validaet', () => {
+      expect(
+        parameters.parse(
+          {
+            stringValue: 'yyyy',
+            numberValue: '0',
+            booleanValue: 'false',
+            arrayValue: '[]',
+          },
+          false
+        )
+      ).toEqual({
+        stringValue: 'yyyy',
+        numberValue: 0,
+        booleanValue: false,
+        arrayValue: [],
+      });
+    });
+
     it('stringify', () => {
       expect(
         parameters.stringify({
@@ -463,6 +517,31 @@ describe('index', () => {
       );
     });
 
+    it('stringify validation error but should not validate', () => {
+      expect(
+        parameters.stringify(
+          {
+            stringValue: 'yyyy',
+            unionStringValue: 'v3' as never,
+            numberValue: 0,
+            unionNumberValue: -1 as never,
+            booleanValue: false,
+            jsonValue: { apiKey: '' },
+            arrayValue: [],
+          },
+          false
+        )
+      ).toEqual({
+        stringValue: 'yyyy',
+        unionStringValue: 'v3',
+        numberValue: '0',
+        unionNumberValue: '-1',
+        booleanValue: 'false',
+        jsonValue: '{"apiKey":""}',
+        arrayValue: '[]',
+      });
+    });
+
     it('stringify required error and validation error', () => {
       expect(() =>
         parameters.stringify({
@@ -474,5 +553,22 @@ describe('index', () => {
         'stringValue is required, numberValue is required, booleanValue is required, arrayValue is required. unionStringValue: the value must be v1 or v2, unionNumberValue: the value must be 0 or 1, jsonValue: apiKey must be specified.'
       );
     });
+
+    it('stringify required error and validation error, but should not validate', () => {
+      expect(
+        parameters.stringify(
+          {
+            unionStringValue: 'v3' as never,
+            unionNumberValue: -1 as never,
+            jsonValue: { apiKey: '' },
+          },
+          false
+        )
+      ).toEqual({
+        unionStringValue: 'v3',
+        unionNumberValue: '-1',
+        jsonValue: '{"apiKey":""}',
+      });
+    });
   });
 });