To provide a finger vein authentication device that, while retaining high authentication accuracy, has high convenience and that uses a vein of a fingertip as a personal authentication device capable of being mounted on a small-size apparatus, such as a cellular phone and a notebook PC. The finger vein authentication device consists of an input device that includes a light source for irradiating light toward a finger and an image sensor for imaging light from the finger through an opening section, and an image processing part for processing an image photographed by the image sensor. The input device includes finger rests for specifying an end of the fingertip and a presentation position in the center, and a light shielding wall between the finger rest and the light source. The light source is located at the fingertip side of the finger mounted on the finger rest and is located on the surface of the input device or at a position lower than the surface, and light from the light source is directed slantingly upward and irradiates the back side of the fingertip, namely a nail side thereof.
