An authentication apparatus is provided. The authentication apparatus acquires a plurality of pieces of registration authentication information each of which is unique to an authentication target. These pieces of registration authentication information are based on biological information obtained from different and the same kind of parts of a living body of a registered user. The authentication apparatus also acquires biological information from a part of the living body selected by a user, and then generates personal authentication information based on the biological information acquired. The authentication apparatus subsequently arranges a collation order of the plurality of pieces of registration authentication information, and then sequentially collates the plurality of pieces of registration authentication information with the personal authentication information in accordance with the collation serial numbers. After that the authentication apparatus notifies an external section of the authentication target whose registration authentication information corresponds to the personal authentication information as an authentication target successfully authenticated.