BIOMETRIC AUTHENTICATION DEVICE, BIOMETRIC AUTHENTICATION METHOD, AND BIOMETRIC AUTHENTICATION PROGRAM

A biometric authentication device includes: a calculation unit that calculates distribution regarding a first similarity between biometric information of a first modality extracted from output of a sensor and the biometric information of the first modality included in registration data; a derivation unit that derives the distribution regarding a second similarity between the biometric information of the first modality of which the first similarity is ranked first and the biometric information of the first modality of which the first similarity is ranked second and lower, among the biometric information of the first modality included in the registration data; and a switching unit that switches a rate for narrowing down registrants included in the registration data to collation target persons to be collated by personal authentication that uses a second modality different from the first modality, based on the distribution regarding the first similarity and the distribution regarding the second similarity.