An authentication apparatus for solving problems involving convenience and security is disclosed. The authentication apparatus according to the present invention is an authentication apparatus having a plurality of authentication mechanisms, the apparatus determining (S23) whether authentication information that has been input by a card reader for inputting authentication information of an object of authentication is that of a user who is capable of changing over the plurality of authentication mechanisms, displaying (S24) a list of the plurality of authentication mechanisms if it is determined that the user is capable of making the changeover, and registering (S26) the authentication mechanism, which has been selected in the display list, as the effective authentication mechanism.