For stereo matching, edge images are extracted from stereo images. An edge mask matching an edge form of a window relating to a reference edge pixel is searched for from among predefined edge masks mapped to predefined edge forms capable of appearing within a predetermined size window having a center of the reference edge pixel among edge pixels of a reference edge image of the edge images. Among edge pixels of a search edge image of the edge images, an edge pixel located at a center of a window having an edge form matching the searched edge mask is searched for and is set to a corresponding edge pixel mapped to a corresponding point with respect to the reference edge pixel. Among the edge pixels of the reference edge image, the reference edge pixel is used to currently search for the corresponding edge pixel from the search edge image.