Abstract: An X-ray shield device according to one embodiment of the present invention comprises an X-ray shielding plate positioned between an X-ray source and a support member for a subject; a shielding plate driving mechanism including a supporting portion for supporting the X-ray shielding plate, the shielding plate driving mechanism being operable to move the shield plate supported by the supporting portion in a movement plane of the shielding plate perpendicular to a path of X-ray irradiation; and an X-ray shielding plate exchanging means for exchanging the X-ray shielding plate supported by the supporting portion for another X-ray shielding plate of different size.