A particle beam rotational irradiation apparatus of the present invention is purported to place in a frame, even in the case of a corkscrew type, a movable floor that is retractable at the time of movement of an irradiation nozzle. According to the particle beam rotational irradiation apparatus (20) of the invention, it is characterized by including: a frame (2) that supports an irradiation nozzle (1) and rotates an irradiation-nozzle support member(12) that is provided on an inner-circumference side of the frame (2) and supports the irradiation nozzle (1) a movable floor (3) that has a roller (6) movable in a circumferential direction centering on a rotation axis of the frame (2) and a movable-floor rail (7) that is provided in the circumferential direction on the inner-circumference side of the frame (2) and supports the roller (6) wherein the irradiation-nozzle support member (12) and the movable floor (3) have their respective coupling portions (9) that are attachable/detachable to/from each other.
