To execute biological identification by efficiently extracting the physical features of a person to be identified.

A first acquisition part 110 acquires first biological information from a person to be identified. A candidate selecting part 116 selects a plurality of candidates corresponding to the person to be identified from registered persons. A difference detecting part 118 detects a difference value between the second biological information of those candidates. A contribution ratio setting part 120 sets the contribution ratio of each part in the similarity decision of the second biological information based on the difference values. A second acquisition part 112 acquires the second biological information from the person to be identified. A specification authenticating part 122 compares the second biological information of the candidate with the second biological information of the person to be identified based on the contribution ratio in order to specify the person to be identified from the candidate.