The display controller displays a first tomographic image of a three-dimensional image consisting of a plurality of tomographic images on a display unit. A first correction unit corrects the boundary of a first region of interest extracted from the first tomographic image, by a correction instruction using a correction instruction region for the boundary of the first region of interest. The first instruction region setting unit sets a first instruction region on a second tomographic image of the plurality of tomographic images. The second correction unit corrects the boundary of a second region of interest extracted from the second tomographic image by setting a second instruction region on the second tomographic image.