To reduce the manufacturing cost with a simple structure, automatically output objective measured data, and automate the measuring work.

The voltage value corresponding to the energy of incident X-rays is outputted to an amplifier 10 by a scintillation counter (X-ray detecting means) 10. The amplifier 11 amplifies the voltage outputted from the scintillation counter 10 and outputs it to a V-F converter 12. The V-F converter 12 integrates the inputted voltage value and outputs a pulse each time the integrated value becomes a fixed magnitude to clear the integrated value. When these actions are repeated, the magnitude of the X-ray energy detected by the scintillation counter 10 is converted into the pulse density with time, and it is automatically counted by a pulse counter 13.