A rotating gantry is characterized in that a shielding material for attenuating a leakage dose of a secondary radiation generated by collision of a charged particle beam with an irradiation subject is provided at a position that is situated at the side opposed to a particle beam irradiation apparatus with respect to the irradiation subject and through which a beam axis of the charged particle beam passes, and wherein the shielding material is disposed in such a way that when the irradiation subject does not exist in the rotating gantry, a beam axis portion thereof that intersects the beam axis of the charged particle beam, is attachable and detachable, or can move in a sliding manner and in the rotation-axle direction of the rotating gantry.
