A processor according to the present invention extracts a target organ from a medical image, sets a plurality of small regions in the target organ, derives first evaluation values that indicate the respective physical quantities of the plurality of small regions, derives at least one second evaluation value that indicates the relation between the first evaluation values in the plurality of small regions, and derives, on the basis of the second evaluation value, a third evaluation value that suggests the presence or absence of abnormality over the entire target organ.