Provided is a user authentication system that can perform user recognition with a higher accuracy based on acquired bodily information of a user, in an environment in which multiple users use multiple types of bodily information acquisition apparatuses to acquire different types of bodily information. The user authentication system (1) includes multiple types of bodily information acquisition apparatuses (10, 20, 30, 40) configured to acquire different types of bodily information for a certain user； a storage unit (8) configured to store pieces of bodily information acquired by the respective bodily information acquisition apparatuses, in association with the certain user； and a user determination unit (7) configured to check whether or not there is a logical discrepancy between new bodily information acquired newly by a certain bodily information acquisition apparatus among the plurality of types of bodily information acquisition apparatuses and other bodily information acquired by a bodily information acquisition apparatus other than the certain bodily information acquisition apparatus, and thereby determine whether or not the new bodily information acquired by the certain bodily information acquisition apparatus relates to the certain user.
