1. An authentication apparatus comprising: an extraction part configured to extract a feature of a face from a face image of a user; a plurality of classifiers configured to identify the user by determining whether or not the feature extracted by the extraction part matches a feature of a face stored in a storage apparatus; a deriving part configured to derive a specific condition based on at least one of the feature extracted by the extraction part and information for authenticating the user; a selecting part configured to select at least one of the classifiers based on the specific condition; and an authentication part configured to authenticate the user when the selected classifier determines that the feature extracted by the extraction part matches the feature of the face stored in the storage apparatus.