A dose distribution measurement device includes at least two cameras (7, 8) arranged on a plane perpendicular to the center axis (CA) of irradiation of a water phantom (3) with a particle beam (4) so as to take an image of light emission of a fluorescent substance containing liquid (5) in the water phantom and a dose distribution calculation and evaluation unit (10) having a spot position determination part (12) 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 (13) for calculating an irradiation dose distribution at the spot position determined by the spot position determination part (12) using a PDD and an OCR stored in a pencil-beam dose-distribution data storage part (16), to add the irradiation dose distribution at each of spot positions.
