1. A medical image-processing apparatus comprising: a display unit configured to display a plurality of medical images of an object obtained at different imaging positions; at least one central processing unit (CPU) configured to: (a) set a common point of interest on each of the medical images in accordance with an operation of an operator; (b) align the medical images on the display unit, with the points of interest on the medical images made to coincide with each other, wherein said alignment comprises panning at least one of the medical images with respect to another of the medical images; and (c) change a display magnification of one of the medical images and automatically to detect any deviation or displacement and to compensate for the deviation or displacement of the points of interest on at least one other medical image by updating the points of interest on the medical images as necessary to keep the points of interest of the other medical image and the magnified image in coincidence with each other on said displayed mages.