When the degree of matching between patterns decreases due to a pattern fluctuation or an appearance fluctuation that has occurred during manufacturing steps, a heavy work burden would be placed on an operator. A data processing unit of a pattern matching apparatus calculates a threshold for determination of matching between a first template image and a partial region of a search target image obtained by capturing an image of the surface of a sample, on the basis of a result of evaluation of a similarity between the search target image and a second template image, the second template image having been captured in a wider range than the first template image.