A recognition system of this invention has feature point detection means (120), Hough transform means (130), and specific pattern output means (140). In the Hough transform means (130), a Hough space is designed so that a magnitude relation of a distance between points in the Hough space is equivalent to a predetermined magnitude relation of an inter-specific-pattern distance indicative of a difference between specific patterns. The recognition system detects the specific patterns using the Hough space. By adopting such a structure to express more similar specific patterns in an image as closer points also in the Hough space, it is possible to achieve an object of this invention.