Disclosed is an authentication apparatus easily achieving convenience and high accuracy in authentication. The authentication apparatus has an authentication accuracy simulation section that simulates authentication accuracy and also has a registration information setting section that sets an ID and biometric information input as registration information. The authentication accuracy simulation section uses an ID and biometric information that has been input as registration information by a user at the time of registration and the registered registration information to simulate authentication accuracy with which the user is authenticated. When the authentication accuracy simulated by the authentication accuracy simulation section does not satisfy a predetermined condition, the registration information setting section rejects registration of the ID input as the registration information.