PROBLEM TO BE SOLVED: To provide a synchrotron accelerator capable of emitting circular beam suitable for irradiation.SOLUTION: A synchrotron accelerator 10 according to an embodiment includes: deflection electromagnets 11 for forming a circular orbit, for forming a circular orbit by making an incident beam circle a deflector 13 for outgoing radiation, for gradually removing beams in a resonance region outside a stable region of the beam when emitting the beam four deflection electromagnets 14 for adjusting the outgoing orbit, arranged in front and rear of the deflector 13 for outgoing radiation with respect to the beam circling direction, and adjusting the outgoing orbit of the beam a deflection electromagnet 15 for outgoing radiation, for taking to the outside the beam taken out from the deflector 13 for outgoing radiation and a control device 17 for controlling an excitation amount of the four deflection electromagnets 14 for adjusting the outgoing orbit. The control device 17 adjusts the position and angle of the outgoing orbit with respect to the position of the deflector 13 for outgoing radiation.
