1. A defect inspection apparatus for inspecting whether or not a product could be correctly manufactured, comprising: a manufacturing desirable image forming circuit for forming a manufacturing desirable image from an original image of the manufacturing desirable image derived from a designing work; an inspection portion setting circuit for setting a portion where a defect may readily occur within said manufacturing desirable image; a partial image having defect pattern forming circuit for superimposing a defect pattern where the defect may readily occur on a partial image made by cutting out said inspection portion of said manufacturing desirable image so as to form a partial image equipped with the defect pattern; a photographing circuit for photographing the manufactured product as an inspection subject; a template matching circuit by which while an image of the inspection subject photographed by said photographing circuit is employed as an input image and said partial image having the defect pattern is employed as a template, said input image is compared with said template; and a defect present/absent judging circuit for judging whether or not the defect is present based upon an evaluation value outputted from said template matching circuit.