A radiation irradiating apparatus includes a processing circuitry. The processing circuitry acquires a past cumulative dose distribution associated with patient identifying information, from a storage that is storable a cumulative dose distribution. The processing circuitry calculates a first cumulative dose distribution and a second cumulative dose distribution during a radiation irradiation to a patient associated with the patient identifying information, the first cumulative dose distribution being a cumulative dose distribution, the second cumulative dose distribution being generated by adding the first cumulative dose distribution to the past cumulative dose distribution. The processing circuitry displays, on a display, at least one of the first and second cumulative dose distributions during the radiation irradiation.
