A radiation measuring device 101 having a plurality of sensors configured to generate charges in response to the radiation includes a signal processing device 205. The signal processing device 205 uses an signal generated by a proton beam irradiation device 102 upon changing of beam energy and causes accumulation values of charges output from the sensors to be separately stored in a main control device 206 for each value of the energy. The main control device 206 calculates depth dose profiles for values of the beam energy from the accumulation values stored in the main control device 206 and representing the charges. The main control device 206 calculates a range of the beam for each of the values of the beam energy from the depth dose profiles, corrects the depth dose profiles for the values of the beam energy using a correction coefficient that depends on the range and sums the corrected depth dose profiles.
