Image data of a three-dimensional region of a medical device placed in a subject body is stored in an image data storage section. An image creating section extracts pixels corresponding to an image of a medical device on the basis of the distribution of pixel values along a plurality of radial rays, which spreads from the axis side of the medical device on a plurality of sectional images perpendicular to the axis of the medical device, using the image data stored in the image data storage section and creates image data, in which the medical device spreads, by distributing the extracted pixels in a flat surface region corresponding to the axis direction and the angular direction of the radial ray.
