Apparatus and method for authentication and method for registering a person

Wrongful authentication process is prevented. A passive entry authenticating section compares an identification signal sent from a portable unit with an identification signal previously stored in a storage section. A biometrics authenticating section compares the biometrics information of a user inputted through a sensor section with the biometrics information registered in a biometrics database. A control section authenticates an authorized user when there is agreement in both the identification-signal comparison result and the biometrics-information comparison result, and controls a lock system to unlock the door lock of the automobile.