1. A vein pattern registration apparatus comprising: an imaging unit for capturing an image of a body surface of a portion of a living body with near-infrared light and generating near-infrared light imaging data; a vein pattern extraction unit for extracting multiple kinds of near-infrared light vein patterns from one piece of the near-infrared light imaging data by applying a differential filter that outputs a large value for a pixel having a large difference between the pixel and its surrounding pixel to a plurality of pixels constituting the near-infrared light imaging data and changing a parameter that changes an output property of the differential filter; a pseudo-vein pattern determination unit for determining presence of a pseudo-vein pattern intentionally formed on a part of the captured body surface based on the extracted vein pattern; and a vein pattern registration unit for registering the near-infrared light vein pattern based on a determination result from the pseudo-vein pattern determination unit to generate a registered vein pattern.