A charged particle beam 2 which enters a final bending electromagnet 7 after traveling through quadrupole electromagnets 4, 5, 6 travels through the final bending electromagnet 7 in an arc shape path by increasing or decreasing a bending magnetic field generated in the final bending electromagnet 7, with a pre-determined period for example and is scanned in an X-direction. The charged particle beam 2 scanned in the X-direction is scanned in a Y-direction while traveling through a Y-direction Wobbler electromagnet 8. Consequently, the charged particle beam 2 is scanned in the X-direction and the Y-direction, and the target 9 is irradiated with the charged particle beam 2 so that a round field is drawn, for example.