1. A medical image processing apparatus comprising: an image information processor that generates image information for acquiring a superposed image having a three-dimensional image of a medical device over a three-dimensional image of a preoperative structure of an object to which the medical device is inserted, and outputs the image information on the superposed image, wherein the image information processor generates a three-dimensional image of the preoperative structure by segmenting a plurality of preoperative two-dimensional tomograms, further wherein each of the two-dimensional tomograms has a marker as a coordinate reference, and wherein the image information processor calculates a form and a position of the medical device from a curvature state of the medical device, a position where the medical device is mounted, and the marker and generates a three-dimensional image of the medical device in the superposed image.