Abstract: An authentication device, an authentication method, and program, that effectively prevent unauthorized access without compromising the convenience of face authentication, are provided. The authentication device 100 includes a first authentication means 110 for performing an authentication of a user based on a face image photographed, and a second authentication means 120 for requesting the user to perform a predetermined motion, for photographing the user performing the predetermined motion, and for authenticating the user based on a motion image photographed, when the authentication in the first authentication means is successful.