PROBLEM TO BE SOLVED: To provide a particle beam treatment apparatus capable of reducing a psychological burden of a patient undergoing cancer treatment more than the conventional one.SOLUTION: The particle beam treatment apparatus includes: a synchrotron 20 for accelerating a heavy particle beam； a beam transport system 15 for transporting the beam accelerated by the synchrotron 20； irradiation systems 10a and 10b having an irradiation device 250 for irradiating a target with the beam transported by the beam transport system 15； a control device 100 for controlling the synchrotron 20, the beam transport system 15, and the irradiation systems 10a and 10b； and a treatment chamber 200 in which the irradiation device 250 of the irradiation systems 10a and 10b is disposed, where a cover 300 of the irradiation device 250 and a side wall 210 of the treatment chamber 200 have such a shape as to be connected by a gentle curve.SELECTED DRAWING: Figure 4
