Charged particle beam irradiation apparatus

A charged particle beam irradiation apparatus comprising:

• a plurality of scanning electromagnets, for irradiating a target with a charged particle beam emitted from an accelerator;
• a quadrupole electromagnet;
• a power source for feeding current to said quadrupole electromagnet;
• and
• a control unit for controlling said current output from said power source;
• wherein two of said plurality of scanning electromagnets include a first scanning electromagnet, and a second scanning electromagnet located downstream of said first scanning electromagnet, and said quadrupole electromagnet which is located between said first and second scanning electromagnets enables adjustment of a phase of betatron oscillation of said charged particle beam, and wherein said control unit controls said current so that a difference between phases in the betatron oscillation of said charged particle beam in said first and second scanning electromagnets is approximately an integer multiple of 180 deg.