A personal authentication system using biometrics information, which identifies or authenticates an individual by verifying to-be-verified biometrics characteristic data against previously registered biometrics characteristic data. The system includes a biometrics information inputting section having a function to acquire the to-be-verified biometrics information; a biometrics information converting section converting said to-be-verified biometrics information, acquired through said biometrics information inputting section, into a state to be acquired on a predetermined acquisition condition, said predetermined acquisition condition being a same condition under which the registered biometric information was acquired; and a biometrics characteristic data extracting section extracting to-be-verified biometrics characteristics data from the to-be-verified biometrics information obtained by the conversion in said biometrics information converting section.