An object of the present invention is to easily maintain the couch positioning accuracy and reduce the couch positioning time while resolving the complexity of input operations by the operator at the time of couch positioning. To accomplish the above object, calculation points are set to a CT image at the time of treatment planning, and the 3D coordinates of the set calculation point are set to a DRR image. When a couch positioning unit 115 loads the DRR image from an image server 109, it reads the coordinates of calculation points set to the DRR image and displays them on the monitor 116 together with the DRR image. Further, when DR image data is loaded into the couch positioning unit 115, the DR image is displayed on the monitor 116 and calculation points set to the DRR image are set also to the DR image.
