Provided are a radiation measurement device and method that allow stable radiation measurement as compared with the prior art. The radiation measurement device includes a radiation detection unit 1 having a scintillator, an optical transmission member 21 for transmitting an optical signal generated in the radiation detection unit, and a signal processing unit 3 for calculating a radiation dose from the optical signal transmitted. The signal processing unit includes a compensation unit 7 for obtaining an optical transmission loss amount from a change in wavelength spectrum in the optical signal caused by radiation acting on the optical transmission member and performs compensation-control on the optical transmission loss amount, and outputs a compensated signal.