PROBLEM TO BE SOLVED: To provide an image processing device capable of locating a position of a metallic body even when the metallic body is deviated from FOV, and in which computing time is short.SOLUTION: An image processing device of the invention comprises a location part for, locating a boundary between a metallic body and a non-metallic body in an image based on X-ray imaging, based on change degree of luminance values in a predetermined direction of the image based on the X-ray imaging.SELECTED DRAWING: Figure 8