A feature amount calculation unit acquires the feature amount of each of a plurality of regions of interest ROI, each of which is designated so as to include one or more different target lesions OL that are lesions in examination images, in examination data including one or more examination images. An individual similarity calculation unit compares the feature amount of each region of interest ROI with a feature amount of a case lesion CL, which is a lesion in a case image registered in a case, and calculates an individual similarity for each region of interest ROI. A similar case search unit calculates a total similarity on the basis of a plurality of calculated individual similarities and searches for a similar case on the basis of the calculated total similarity.
