1. A pattern model positioning method in image processing of, upon searching out of an image to be searched and positioning an object to be searched that is similar to a pre-registered image by use of a pattern model corresponding to the registered image, positioning with accuracy higher than at an initially given position, the method including the steps of: extracting a contour from the registered image; constructing a pattern model of the registered image, in which a plurality of reference points are set on the extracted contour, and also a corresponding point search line having a predetermined length and passing through each reference point as well as being substantially orthogonal to the contour is also allocated to each reference point; acquiring an image to be searched, and also arranging the pattern model so as to be superimposed on the image to be searched in accordance with an initial position included in the image to be searched and corresponding to the registered image; finding a corresponding edge point on the image to be searched corresponding to a reference point of each corresponding point search line of the pattern model out of each pixel in the image to be searched that is positioned as superimposed on the corresponding point search line upon superimposing the pattern model on the initial position on the image to be searched; and taking a distance between each corresponding edge point and a contour including the reference point corresponding to the corresponding edge point as an evaluation value, and performing fine positioning with accuracy higher than accuracy in the given initial position such that an absolute value of an accumulated value of the evaluation values becomes minimal.