PURPOSE: To detect the image matched with a designated image at high speed and by comparatively little processing amount in a processing object image.

CONSTITUTION: From processing object data, a candidate run (picture element column composing an object image and picture element column with high matching degree) is read from a work memory (22). A designated reference image is magnified or reduced by a magnification/reduction ratio (k) determined by a calculation (24). A template matching is performed for this magnified or reduced reference image and the image of the vicinity area of the candidate run (25). When the matching is judged as a result of the matching (26 and YES), the coordinate of the center picture element of the matched image is stored in the work memory (27).