A radiation measurement device comprising a calculation unit in which respective wave height values of voltage pulses from a radiation detector (1, 3) are made to correspond to radiation energy values and a count that is the number of the voltage pulses is separately generated for each of a plurality of channels corresponding to the wave height values so that a wave height spectrum is generated and a dose of a radiation that has entered the radiation detector (1, 3) is calculated based on the wave height spectrum, wherein the calculation unit comprises: - a spectrum generation unit that is configured to generate the wave height spectrum; - a dose rate calculation unit that is configured to calculate a dose in the radiation energy value corresponding to each of the channels, based on a count generated in each channel by the spectrum generation unit, to integrate the calculated dose for the whole measurement range for the radiation energy value so as to obtain an integral dose, and to divide the integral dose by a measurement time so as to obtain a dose rate; characterized in that it further comprises - a correcting dose rate calculation unit that is configured to calculate a neglected dose rate which is a dose rate distributed at an energy the same as or smaller than a measurement limit of the measurement range of the radiation energy values and which is not reflected in the dose rate calculated by the dose rate calculation unit, based on a count in at least one channel that includes a lower limit within the measurement range, out of counts generated in the respective channels by the spectrum generation unit, and based on the energy resolution of the radiation detector (1, 3), and to obtain a correcting dose rate, that is a radiation dose per unit time, from the calculated dose rate; and - a dose rate correction calculation unit that is configured to multiply the correcting dose rate obtained by the correcting dose rate calculation unit by a correction coefficient, obtained based on the energy resolution of the radiation detector (1, 3), and to calculate a dose rate of a radiation that has entered the radiation detector (1, 3) by adding the multiplied correcting dose rate to the dose rate obtained by the dose rate calculation unit. - a spectrum generation unit that is configured to generate the wave height spectrum; - a dose rate calculation unit that is configured to calculate a dose in the radiation energy value corresponding to each of the channels, based on a count generated in each channel by the spectrum generation unit, to integrate the calculated dose for the whole measurement range for the radiation energy value so as to obtain an integral dose, and to divide the integral dose by a measurement time so as to obtain a dose rate; characterized in that it further comprises - a correcting dose rate calculation unit that is configured to calculate a neglected dose rate which is a dose rate distributed at an energy the same as or smaller than a measurement limit of the measurement range of the radiation energy values and which is not reflected in the dose rate calculated by the dose rate calculation unit, based on a count in at least one channel that includes a lower limit within the measurement range, out of counts generated in the respective channels by the spectrum generation unit, and based on the energy resolution of the radiation detector (1, 3), and to obtain a correcting dose rate, that is a radiation dose per unit time, from the calculated dose rate; and - a dose rate correction calculation unit that is configured to multiply the correcting dose rate obtained by the correcting dose rate calculation unit by a correction coefficient, obtained based on the energy resolution of the radiation detector (1, 3), and to calculate a dose rate of a radiation that has entered the radiation detector (1, 3) by adding the multiplied correcting dose rate to the dose rate obtained by the dose rate calculation unit.