The invention discloses a beam scheduler and a beam distribution method of the beam scheduler. The invention aims to realize the effective utilization of a particle beam irradiation facility. When an irradiation request is received from one of a plurality of irradiation chambers (A-D) , the beam scheduler (1) in the invention adds maximum allowable waiting time at the end of beam distribution to the irradiation request, adds the irradiation request to the end of a waiting list, judges whether prediction waiting time at the end of distributing beam to one irradiation chamber is beyond the maximum allowable waiting time, brings forwardly the irradiation request in the waiting list when the prediction waiting time is beyond the maximum allowable waiting time, and distributes beam to the irradiation chamber corresponding to the highest-level irradiation request in the waiting list.
