An X-ray CT system according to the invention includes a holding plate which holds X-ray shield plates, a first support plate which supports one short-directional end portion of the holding plate, the first support plate conforming to a bend of the holding plate, a second support plate which supports another short-directional end portion of the holding plate, the second support plate conforming to the bend of the holding plate, and grooves continuously formed on the respective components when the holding plate, the first support plate, and the second support plate are assembled.