if (typeof signInPayload !== 'undefined') {
    amazon.Pay.renderButton('#AmazonPaySinginButton', {
        // set checkout environment
        merchantId: 'A10U569M21U863',
        ledgerCurrency: 'JPY',
        // sandbox: false,
        // customize the buyer experience
        checkoutLanguage: 'ja_JP',
        productType: 'SignIn',
        placement: 'Cart',
        buttonColor: 'LightGray',
        // configure sign in
        signInConfig: {
            payloadJSON: signInPayload, // string generated in step 2
            signature: singInResultSignature, // signature generatd in step 3
            publicKeyId: 'AEU7G26EQQ72GWNPGRTNP7ZK'
        }
    });
}