A particle beam treatment system includes an accelerator system (2) that accelerates a charged particle beam and a beam transport system (3) that transports a high-energy beam emitted from the accelerator to an irradiation location, wherein the beam transport system (3) is provided with at least one steering electromagnet (33) and at least one beam position monitor (34) corresponding to the at least one steering electromagnet (33), and wherein the at least one beam position monitor (34) supplies an excitation current for correcting a beam position, which periodically varies, to the at least one steering electromagnet (33).
