The invention is intended to confirm whether the SOBP (spread-out Bragg peak) width is a desired value in real time during beam irradiation, and to improve safety in treatment. Ion beam delivery equipment comprises a beam generator including a synchrotron, an RMW (range modulation wheel) device for forming an SOBP width of an ion beam extracted from the beam generator, a beam delivery nozzle including a reference dose monitor and a main dose monitor which are installed respectively upstream and downstream of the RMW device in the direction of travel of the ion beam, and an SOBP width computing unit for computing the SOBP width of the ion beam, which is formed by the RMW device, based on values detected by both the reference dose monitor and the main dose monitor.