A finding classification unit classifies a target region included in an examination image into a plurality of lesion regions indicating a plurality of findings to generate a finding classification result. A first search unit searches for a case image similar to an examination image as a first similar case image from a case database DB based on the finding classification result. A display controller displays the examination image and the first similar case image. A key finding specification unit receives designation of a position of a key finding to the displayed examination image to specify a position of the key finding and specifies a finding name of the key finding having the position specified. A second search unit further searches for a case image associated with the specified position and the finding name of the key finding from the first similar case image to acquire a second similar case image.