A stereo matching processing system includes an associating unit that associates with each other such regions, in a plurality of images obtained by shooting a same object from different directions, that are on a same scanning line and have a largest correlation coefficient between them, as items that represent a same position, and a line segment determining unit that determines whether or not line segments that are associated with each other as items that teach a same position are drawn in the plurality of images respectively. When said line segment determining unit determines that the line segments are drawn, said associating unit associates with each other, not such regions that are on the same scanning line and have a largest correlation coefficient between them, but intersections at which the scanning line and the line segments each cross, as items that represent a same position.