1. A personal identification apparatus comprising: a plurality of light sources for irradiating light to a finger; an image pickup unit being influenced by external light, for picking up an image by using light from a finger which is irradiated by only the external light or by both of the external light and said plurality of light sources; a light source power control unit for changing light power of each of said plurality of light sources; a sensitivity control unit for changing gain of an image pickup element in the image pickup unit; and a processing unit for conducting personal identification by extracting a blood vessel pattern from an image picked up by said image pickup unit, wherein: said processing unit extracts a partial region from the picked up image and controls one of said light source power control unit or said sensitivity control unit based on information in the partial region.