There is provided a rotating irradiation apparatus that can secure as large an access floor as possible, reduce noise during the formation of an access floor, and stably operate with a simple structure. The rotating irradiation apparatus includes an irradiation device 7 that irradiates a charged particle beam, a frame 1 on which the irradiation device is mounted and which rotates the irradiation device so that a patient lying on a treatment table 8 fixed to a stationary floor surface is irradiated with the charged particle beam, a ring 10 that is rotatably held on an inner periphery of the frame, an opening/closing-type floor 20 which is provided inside the ring and of which a portion through which the irradiation device passes is openable and closable, and drive means 28 that reversely rotates the ring in synchronization with the rotation of the irradiation device so as to maintain the opening/closing-type floor horizontal.
