1. An image defect inspecting apparatus for comparing a reference image data with a scanned image for inspection, which is output based on the reference image data from an image output apparatus and is formed on an image recording medium, to judge as to whether an image defect is present on the scanned image for inspection, the image defect inspecting apparatus comprising: an image acquiring unit for acquiring the scanned image for inspection output from the image output apparatus to convert the acquired scanned image for inspection into digital data; a storage unit for storing the reference image data and the digital data converted by the image acquiring unit; a template image producing unit for producing a template image from the reference image data; a corresponding image extracting unit for extracting a predetermined image located at a position corresponding to the template image from the digital data stored in the storage unit; a data embedding unit for embedding desirable same pattern data into the template image and the predetermined image extracted by the corresponding image extracting unit; a normalized correlation value calculating unit for calculating a normalized correlation coefficient from the template image and the extracted image, into which the same pattern data are embedded by the data embedding unit; and a defect judging unit for comparing the normalized correlation coefficient calculated by the normalized correlation value calculation unit with a predetermined threshold value to obtain large and small relation therebetween so that it is judged whether the scanned image for inspection contains a defect.