To reduce the possibility of the denial of a registerer even when performing personal authentication by a face image according to the combination of various face direction conditions and illumination conditions.

Face featured values are calculated from a photographed face image (S211), and the similarity of the face featured values and already registered face featured values is calculated (S212), and when the similarity is larger than a similarity maximum value Pmax (S213), the similarity is set as the similarity maximum value Pmax (S214). When the similarity maximum value Pmax is not less than a first threshold Th1 (S215), the arithmetic operation (S216) of the face direction conditions of the face image and the arithmetic operation(S217) of illumination conditions are executed, and when the face featured values corresponding to the combination of the face direction conditions and the illumination conditions are not registered yet (S218), the face featured values are additionally registered by making them correspond to the combination of the face direction conditions and the illumination conditions (S219). When the similarity maximum value Pmax is less than a second threshold Th2 (S220), the photographed person is not authenticated as a registered person (S222), and when the similarity maximum value Pmax is not less than the second threshold Th2 (S220), the photographed person is authenticated as the registered person (S221).

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