An apparatus acquires information on a user's finger veins for personal authentication and includes: guides which form a space to put the user's finger in and block external light to come into the space sideways; a door assembly which closes when the user's finger is not in place and opens downward by a pushing force of the user's finger when the user's finger is in place, and blocks external light from above the space; a light source section disposed on a surface of the door assembly surface for irradiating the user's finger with light; a filter located at a space bottom and having a reflective surface for reflecting external light coming into the space or light from the light source section; and an imaging unit located under the filter for taking an image of veins of the user's finger exposed to the light emitted from the light source section.