Provided is a radiation monitor and the like capable of appropriately measuring radiation. A radiation monitor (100) includes: radiation detection units (11, 12); optical fibers (13p, 13q) that transmit light generated by a plurality of radiation detection elements (11a, 12a) to merge; a light detection unit (14) that converts the light after merging guided to the light detection unit into an electric pulse; a measurement device (15) that calculates a dose rate of radiation based on a count rate of the electric pulses; and an analysis/display device (16). Housings (11b, 12b) include a housing (11b) made of a first material and another housing (12b) made of a second material.