Abstract: A matching device comprises a monitor screen on which first and second images containing a common object are indicated. First, an arbitrary pixel, contained in the first image, is designated as a designating point. Then, four optimum searching pixels are selected from the first image. The optimum searching pixels exist close to the designating point, and have a pixel value more different from the designating point than pixel values of the other pixels around the optimum searching pixels. A candidate point and candidate point surrounding pixels, which correspond to the designating point and the optimum searching pixels, are detected in the second image.