A particle-beam control electromagnet capable of shortening a transportation path of a particle beam and an irradiation treatment apparatus which contributes to miniaturization and weight reduction of the rotating gantry supporting this control electromagnet are provided. The electromagnet includes a first superconducting coil group, a second superconducting coil group, and a vacuum vessel. The first superconducting coil group forms at least one of a bending magnetic field and a focus/defocus magnetic field. The second superconducting coil group is placed around the trajectory of the particle beam at the end of the first superconducting coil group and forms correction magnetic fields for correcting the trajectory of the particle beam. The vacuum vessel hermetically houses the first superconducting coil group, the second superconducting coil group, and a cooling medium, and insulates from the outside air.