A biometric authentication unit includes a position detecting section for detecting a users finger position from a pressure distribution detected by a right-side pressure detecting plate, a left-side pressure detecting plate, a front-side pressure detecting plate, a rear-side pressure detecting plate and a fingertip pressure detecting plate corrects a finger vein pattern of a registrant data on the basis of the difference between the detected users finger position and a correct position collates the acquired users finger vein pattern with the corrected registrant data and authenticates whether the user is the registrant.
