A control unit is provided with, a retaining section that retains a plurality of operation patterns each being a pattern of operation to be periodically repeated by an accelerator, the operation patterns having respective operation conditions adjusted for different emission times of an particle beam, to cause a deflection electromagnet in the accelerator to have an intended magnetic field intensity even under a presence of a hysteresis; a reading section for a plurality of slices of an irradiation target in a depth direction, which reads an irradiation condition for each of the slices; a selection section that selects the operation pattern suitable for each of the slices, on the basis of the read irradiation condition; and a main control section that controls, for each of the slices, the accelerator on the basis of the selected operation pattern and an irradiation device on the basis of the irradiation condition.