1. An image processing apparatus comprising: a target finding acquisition unit configured to acquire a target finding of a medical image; a feature quantity calculation unit configured to calculate an image feature quantity of a type associated in advance with the target finding acquired by the target finding acquisition unit, for each of a plurality of cross-sectional images of the medical image; and a cross-sectional image identification unit configured to identify one of the plurality of cross-sectional images based on the image feature quantity calculated by the feature quantity calculation unit.