An authentication apparatus includes a registration unit that registers authentication information representing a check target, a first authentication unit that authenticates the check target at the entrance of the check target to a first area, a second authentication unit that authenticates the check target at the entrance of the check target to a second area after being authenticated by the first authentication unit, and a detector that detects a check target present in a detection area and expected to be authenticated by the second authentication unit. The second authentication unit retrieves, from the registration unit, registration information of the check target detected by the detector, and authenticates the check target authenticated by the first authentication unit using the registration information.