A therapeutic device is provided, including a cylindrical gantry； a pedestal, a particle beam irradiation device, a first rail, and a second rail all disposed in the gantry； the first rail including an arc-shaped portion and a straight portion, the second rail having a same shape as the first rail, a rail motor on the second rail to rotate the second rail in a opposite direction than that of the gantry, first and second moving floors on the rails and respectively including first floor panels rotatably connected to each other and second floor panels rotatably connected to each other, a first end panel of the first floor and a fourth end panel of the second floor being detachably connected to the irradiation device, and a second end panel of the first floor being detachably connected to a third end panel of the second floor.
