A pathology diagnostic apparatus (10) includes an image divider (130) that divides an image in which a body part to be diagnosed appears into a plurality of regions based on luminance values of pixels included in the image； a contour extractor (150) that extracts a contour in one region selected from the plurality of regions； a lesion region identifier (170) that identifies a lesion region appearing in the image by using the extracted contour； and a diagnosis result outputter (190) that presents the identified lesion region.
