PATTERN INSPECTION APPARATUS AND PATTERN INSPECTION METHOD

A pattern inspection apparatus includes an optical image acquisition mechanism to acquire an optical image of each of a plurality of regions on the inspection substrate where a pattern is formed, a plurality of comparison circuits to individually compare the optical image with a reference image corresponding to the optical image, an abnormality determination circuit to determine, based on comparison results, whether there is a region having an inspection abnormality in the plurality of regions, a malfunction diagnosis circuit to diagnose whether a comparison circuit that performed comparison for the region determined to have the inspection abnormality in the plurality of regions has a malfunction, and an assignment processing circuit to individually assign regions of the plurality of regions where comparison is to be performed to comparison circuits that are not diagnosed as malfunctions, and to exclude a comparison circuit diagnosed as a malfunction from the region assignment target.