Person authentication method

A person authentication method comprising:

• obtaining, from a medium carried by a person who passes through a first position, first information indicating gender and age of the person;
• performing a first authentication operation with respect to a person whose face image is included in a first image obtained by capturing a person passing through the first position;
• setting, as the first authentication operation, an authentication operation to be performed using a face image of a person having gender and age specified in the first information;
• storing history information of the first authentication operation in a corresponding manner to first identification information of a person who is successfully authenticated in the first authentication operation,
• obtaining, from a medium carried by a person who passes through a second position at downstream side of the first position in direction of traffic of persons, second identification information of the person,
• performing a re-authentication operation with respect to a person with face image included in a second image that is taken by capturing a person passing through the second position,
• retrieving, from the first memory, the history information matching with a predetermined reconfirmation history condition, and
• performing the re-authentication operation only when the second identification information matches with the first identification information that is stored in a corresponding manner to the retrieved history information.