A dose distribution calculation device of the invention is characterized by including: a beam information storing unit (a measured energy storing unit, a measured electric-charge storing unit, a measured beam-central axis storing unit), in which, when particle beam information of a particle beam generated by a particle beam therapy system is measured by a measuring device in confirmative radiation in which the particle beam is radiated to a phantom as a substitute for a treatment target, the thus-measured particle beam information is stored; and a total dose calculation unit for calculating a radiation dose distribution (a total dose distribution) on the basis of the measured particle beam information (a measured energy, a measured beam quantity (a measured number of electric charges), a measured position of beam central axis).