1. A matching device for processing first and second images in which a common object is photographed, to detect a corresponding point, which is contained in said second image and corresponds to a designating point contained in said first image, said device comprising: means for designating an arbitrary pixel, contained in said first image, as said designating point; means for selecting at least one optimum searching pixel from said first image, said optimum searching pixel existing close to said designating point, and having a pixel value more different from said designating point than pixel values of the other pixels around said optimum searching pixel; means for obtaining candidate points and candidate point surrounding pixels that correspond to said designating point and said optimum searching pixel, respectively, said candidate points and said candidate point surrounding pixels being contained in said second image; means for calculating an error based on pixel values of said designating point, said optimum searching pixel, said candidate points, and said candidate point surrounding pixels; and means for extracting one of said candidate points, by which said error becomes the minimum, as said corresponding point corresponding to said designating point.