An authentication apparatus for authenticating an authentication target of a user's face includes: a display configured to display an image to authentication target; a camera arranged in the vicinity of the display to take an image of the authentication target; an assist unit configured to output a guide image instructing a user a direction in which to turn in accordance with an attribute of the authenticating; and an image synthesis unit configured to synthesize the image taken by the camera and the guide image output from the assist unit to display a synthesized image on the display.