Abstract: The present invention provides a biometric authentication system including: a parameter manage server having a user parameter generating portion for generating a user parameter using a user ID transmitted from a client terminal, a master key and a temporary parameter; the client terminal having an input unit by which a user ID provided in advance for a user is input, a biological information sensor which acquires biological information of a user, a feature extracting portion which extracts feature from the biological information acquired by the biological information sensor and a transforming portion which transforms the feature using the user parameter generated by the parameter manage server to generate transformation feature; and an authentication server having a matching portion which matches the transformation feature transmitted from the client terminal against a template stored in advance in the storing portion.