The present invention is an authentication apparatus comprising: a prism of an approximately quadrangle-frustum shape, the prism of the approximately quadrangle-frustum shape is arranged so that a bottom side, out of two parallel surfaces of the prism of approximately quadrangle-frustum shape, is a placing surface side for a finger; a first imaging means is arranged below a top surface parallel to the bottom surface, the first imaging means that images an image of the finger transmitted through the top surface; a light source that radiates light to at least one side surface of a first set of side surfaces, out of two sets of side surfaces of the approximately quadrangle-frustum shape that face each other; and a second imaging means that images the image of the finger transmitted through a second set of side surfaces, out of the two sets of side surfaces.