A radiation measurement device comprising: a first pulse height detection circuit for outputting a first pulse height detection signal which rises when a detection pulse outputted from a radiation detector becomes greater than a lower threshold Lsh, and falls when the detection pulse becomes smaller than the lower threshold Lsh; a second pulse height detection circuit for outputting a second pulse height detection signal which rises when the detection pulse outputted from the radiation detector becomes greater than an upper threshold Hsh greater than the lower threshold Lsh, and falls when the detection pulse becomes smaller than the upper threshold Hsh; a crystal oscillator for generating a clock pulse with a certain cycle; a first rising and falling detection circuit for detecting both rising and falling edges of the first pulse height detection signal outputted from the first pulse height detection circuit , in synchronization with the clock pulse from the crystal oscillator ; a second rising and falling detection circuit for detecting both rising and falling edges of the second pulse height detection signal outputted from the second pulse height detection circuit , in synchronization with the clock pulse from the crystal oscillator ; and a combining circuit for outputting a signal corresponding to the detection pulse that is within a range between the lower threshold Lsh and the upper threshold Hsh, by combining an output from the first rising and falling detection circuit and an output from the second rising and falling detection circuit , in synchronization with the clock pulse from the crystal oscillator . a first pulse height detection circuit for outputting a first pulse height detection signal which rises when a detection pulse outputted from a radiation detector becomes greater than a lower threshold Lsh, and falls when the detection pulse becomes smaller than the lower threshold Lsh; a second pulse height detection circuit for outputting a second pulse height detection signal which rises when the detection pulse outputted from the radiation detector becomes greater than an upper threshold Hsh greater than the lower threshold Lsh, and falls when the detection pulse becomes smaller than the upper threshold Hsh; a crystal oscillator for generating a clock pulse with a certain cycle; a first rising and falling detection circuit for detecting both rising and falling edges of the first pulse height detection signal outputted from the first pulse height detection circuit , in synchronization with the clock pulse from the crystal oscillator ; a second rising and falling detection circuit for detecting both rising and falling edges of the second pulse height detection signal outputted from the second pulse height detection circuit , in synchronization with the clock pulse from the crystal oscillator ; and a combining circuit for outputting a signal corresponding to the detection pulse that is within a range between the lower threshold Lsh and the upper threshold Hsh, by combining an output from the first rising and falling detection circuit and an output from the second rising and falling detection circuit , in synchronization with the clock pulse from the crystal oscillator . <EOS>