In biometric authentication, the biometric data is registered and authentication is done by collation input biometric data with the registered biometric data. If the registered biometric data is stolen, there is a possibility that the the biometric data of registrants may be used improperly. It is very difficult to prevent such improper use because we no longer change biometric data. Therefore it is necessary to pay sufficient attention to the protection of biometric data. This paper proposes the application of one way function to biometric authentication in order to protect biometric data of registrants. We examine and discuss the possibility of application of one way function in biometric authentication.