1. An image inspection method executed by an image inspection apparatus, the method comprising: an acquisition step of acquiring an inspection target object image obtained by capturing an image of an inspection target object; a setting reading step of reading, from a storage device that stores inspection region defining information in advance, the inspection region defining information; an inspection region extraction step of extracting, as an inspection region image, a portion to be an inspection region from the inspection target object image, based on the inspection region defining information; and an inspection processing step of performing inspection on the inspection target object by analyzing the inspection region image, wherein the inspection region defining information comprises information defining an initial contour of the inspection region and information defining a range based on the initial contour as a search range for searching a contour of the inspection region, and wherein the inspection region extraction step comprises: a base point setting step of setting a plurality of base points on the initial contour; an edge searching step of performing edge search processing on a line that passes through each base point and intersects with the initial contour, within an region of the search range of the inspection target object image, to determine an edge point corresponding to each base point; and a contour generation step of connecting or approximating a plurality of the edge points respectively corresponding to the plurality of base points to generate the contour of the inspection region of the inspection target object image.