Biometric authentication system and biometric authentication device

This biometric authentication system is provided with: a server (2) that associates and stores pre-registered biometric information, i.e., registered biometric information, with identification information; and a biometric authentication device (1) that performs biometric authentication. A biometric authentication device (1) is provided with: a storage unit (15) that stores a plurality of registered biometric information items; a sensor (12) that acquires biometric information of a user as input biometric information; an input device (11) that acquires identification information of the user; and a verification unit (14) that verifies the registered biometric information and the input biometric information. The matching unit (14) determines whether or not identification information of the user is acquired, performs one-to-many authentication for matching the plurality of registered biological information stored in the storage unit (15) with the input biological information when the identification information of