1. An image comparison system comprising: means for inputting three-dimensional data of an object; reference image storing means for storing a reference image of at least one reference object; pose candidate deciding means for generating a plurality of pose candidates; comparison image generating means for generating, for the reference image for the at least one object, a comparison image close to the reference image, said generating including projecting the three-dimensional data onto a two-dimensional image in accordance with each of the plurality of pose candidates to generate a plurality of comparison images and calculating, for each of the plurality of comparison images, the minimum distance between the comparison image and the reference image and selecting, as the comparison image close to the reference image, the comparison image having the smallest minimum distance; reference correction coefficient storing means for storing a correction coefficient corresponding to the reference image; image comparing means for determining one of a minimum distance value and a maximum similarity degree between the reference image and the generated comparison images; and correcting means for correcting, based on the correction coefficient, one of the minimum distance value and the maximum similarity degree determined by the image comparing means, wherein the image comparing means performs a comparison between the reference image and each of the generated comparison images on the basis of one of the minimum distance value and the maximum similarity degree corrected by the correcting means and, based on a result of the comparison, identifies whether a match exists between any of the generated comparison images and of the reference image.