Synchrotron and particle therapy system using the same

A synchrotron that accelerates and decelerates a charged particle beam that circulates in the synchrotron, comprising:

• a first extraction deflector and a second extraction deflector that are used to extract the accelerated or decelerated beam from the synchrotron;
• a plurality of deflection magnets and a first single quadrupole magnet that are arranged between the first and second extraction deflectors, the first single quadrupole magnet being arranged between any deflection magnets among the plurality of deflection magnets;
• a second quadrupole magnet that is arranged on the upstream side of the first extraction deflector in a traveling direction of the charged particle beam on a path of the circulating charged particle beam;
• and
• a third quadrupole magnet that is arranged on the downstream side of the second extraction deflector in the traveling direction of the charged particle beam on the path of the circulating charged particle beam.