The present invention is an authentication device that has a prism body, an imaging unit, and a visible-light light source that illuminates a body part with visible light. The prism body is provided with the following: a body-part contact surface that makes contact with the aforementioned body part an imaging-unit-side imaging surface that shares an edge with the body-part contact surface a first reflecting surface where a reflector is formed that faces the imaging surface, shares an edge with the body-part contact surface, forms an angle less than or equal to the critical angle with respect to incident light from concavities in the body part, and reflects incident light from convexities on the body part towards the imaging surface and a second reflecting surface where a reflector is formed that faces the imaging surface, shares an edge with the first reflecting surface, and reflects incident light from the body-part concavities and incident light from the body-part convexities towards the imaging surface. The imaging unit images light that passes through the imaging surface, namely the light, reflected by the first reflecting surface, from the body-part convexities and the light, reflected by the second reflecting surface, from the body-part concavities and convexities.Linvention concerne un dispositif dauthentification comprenant un corps de prisme, une unité dimagerie et une source de lumière visible qui éclaire une partie corporelle avec une lumière visible. Le corps du prisme est pourvu : dune surface de contact de partie corporelle qui est en contact avec la partie corporelle précitée dune surface dimagerie du côté de lunité dimagerie qui partage un bord avec la surface de contact de la partie corporelle dune première surface réfléchissante où un réflecteur est formé qui fait face à la surface dimagerie, partage un bord avec la surface de contact de la partie corporelle, forme un angle inférieur ou égal à langle critique par rapport à la lumière incidente de
