A photographed body authenticating unit includes a control unit for executing solid judgment processing for judging whether a photographed body is solid or not based on an entire brightness changing amount of an entirety of a photographed body and a partial brightness changing amount of a part of the photographed body. The entire and partial brightness changing amounts are acquired by a difference between photographed image data obtained in different illuminating states. The control unit also executes photographed body collation processing for collating whether the photographed body is already registered with respect to at least one photographing image or not and authentication processing for authenticating that the photographed body is true when the solid judgment processing determines that the photographed body is solid and the collation processing determines that the photographed body is already registered.