Biometric authentication system and registration method

A biometric authentication system utilizes information of a palm of a hand of a body to perform individual authentication. A processing unit obtains an image of the palm of the hand of the same body a plurality of times from an image capture unit (1-1), judges (38) the degrees of similarity among characteristic data sets of a plurality of images of the palm of the hand, and registers (42) a plurality of characteristic data sets with a high degree of similarity in a storage unit (4a). The shape of the hand in the image is checked (30) from features of the image of the palm of the hand, so it is possible to rapidly judge whether image capture has been successful and extract characteristic data, and registration processing can be executed in a short length of time.