PROBLEM TO BE SOLVED: To provide a radiation dose distribution-measuring system and a radiation dose distribution-measuring method therein, capable of measuring radiation dose distribution data having high position resolution in a short time.SOLUTION: A radiation dose distribution-measuring system includes: a first radiation dose detector 11 for detecting a radiation dose of a particle beam b installed on the upstream of a phantom 12 with respect to an irradiation direction of the particle beam b a second radiation dose detector 13 for detecting a radiation dose of the particle beam b a driving mechanism K for moving the second radiation dose detector 13 position monitoring means 9c for monitoring a position of the second radiation dose detector 13 and radiation dose calculation means 9d to which the respective radiation dose information from the first and second radiation dose detectors 11, 13 and the positional information showing the position of the second radiation dose detector 13 are input. The radiation dose calculation means 9d calibrates the radiation dose information from the second radiation dose detector 13 on the basis of the radiation dose information from the first radiation dose detector 11, and calculates radiation dose distribution data of the particle beam b for a position in the phantom 12 using the positional information of the second radiation dose detector 13.
