1. A region-of-interest determination apparatus comprising an image processor configured to: calculate a degree of a defect based on at least a plurality of kinds of defect attribute information regarding defect data, the defect data including an image corresponding to a defect position detected on a specimen by inspection thereof or an image corresponding to a defect position predicted to be likely to develop a defect on the specimen, both images being obtained by imaging; and extract the defect data of which the degree is higher than a predetermined level, and determine a region to be observed or inspected on the specimen based on the extracted defect data, wherein at least one of said plurality of kinds of defect attribute information is pattern grouping information about the defect data.