Particle therapy system

A particle therapy system, comprising:

• an accelerator which generates a charged particle beam for extraction;
• an irradiation apparatus which irradiates the charged particle beam to an irradiation target;
• a gantry which rotates together with the irradiation apparatus;
• and
• an MRI apparatus which rotates together with the gantry,
• wherein the MRI apparatus includes a magnetic circuit having an iron core and a plurality of coils serving as a magnetic flux source,
• wherein the iron core includes two oppositely disposed magnetic poles, and a member for connecting the magnetic poles,
• wherein at least one of the magnetic poles has a cavity,
• wherein the charged particle beam passing through the cavity is irradiated to the irradiation target, and
• wherein the MRI apparatus is movable to a direction of a rotation axis of the gantry.