To provide an authentication method capable of user authentication using biological information for widespread users having various types of physical features.

This authentication device 15 reads out a user ID from a card 14 for authentication and then reads out biological information of designated type from the biological information corresponding to the read-out user ID. The authentication device 15 detects the biological information of the designated type from the users, compares the read-out biological information with the detected biological information, and authenticate validity of the users based on the comparative results.