A dose distribution measurement device includes at least two cameras arranged on a plane perpendicular to the center axis of irradiation of a water phantom with a particle beam so as to take an image of light emission of a fluorescent substance containing liquid in the water phantom and a dose distribution calculation and evaluation unit having a spot position determination part for determining, from data of the camera image taken with the cameras, the position of a spot Irradiated with the particle beam during its staying and a dose addition part for calculating an irradiation dose distribution at the spot position determined by the spot position determination part using a PDD and an OCR stored in a pencil-beam dose-distribution data storage part, to add the irradiation dose distribution at each of spot positions.
