The energy for providing a kind of accelerator permission ion beam has difference effective for transmitting. Accelerator has circular vacuum container comprising a pair of of annular return yoke facing each other. Injection electrodes 18 are positioned to draw path more towards the line of entrance side in vacuum tank of the return yoke than central axis. In return yoke, six magnetic poles are configured to the radially surrounding injection electrode 18 from injection electrodes 18. Six recess portions are arranged alternately, thus each magnetic pole circumference return yoke. The track concentric region that the inside of vacuum tank is formed, plurality of light beam revolution track 78 exist around injection electrodes 18, and area periphery, the off-centered region of track, plurality of BEAM SQUINT center revolution track exists from injection electrodes 18. The line of the injection electrodes 18 that become close between the off-centered region of track, the beam rotary motion trace 78 and entrance draws path, is basic point with injection electrodes 18, and the line of 180 ° in sight and entrance draws path, and the track 78 of revolving of the interval between the light beam is wider.
