An internal tissue including a lesion region in the human body is modeled as a three-dimensional model. By reconstructing thickness or flexibility of a lumen wall portion including the lesion region and making it possible to confirm a motion of the lumen wall or a flow of fluid in the inside of the lumen wall, a state of the lesion region in the lumen can be confirmed clearly by visual inspection or the like. As a result, the diagnosis in the lumen can be made easier.
