1. A personal authentication apparatus for certifying that a user is a person himself, comprising: an image pickup unit for taking a face-picture of said user; a particular person comparing unit for comparing said user's face-picture taken by said image pickup unit with a face-picture of a particular person held in advance; a personal picture acquiring unit for acquiring the face-picture of said person himself from a memory; and an authentication unit for deciding whether or not said user's face-picture taken by said image pickup unit is identical with the face-picture of said person himself acquired by said personal picture acquiring unit by a different method based upon the comparison result by said particular person comparing unit.