PURPOSE: To perform the said quantitative analysis economically with small sized analysis element, by giving mixed gas between the transmitted and receiver using ultrasonic ceramic microphone and detecting the phase of ultrasonic wave received based on the measured gas.

CONSTITUTION: In the hollow in the cylinder external wall 3 coupling the transmission side ceramic microphone 1 converting electric energy into ultrasonic wave and the reception side ceramic microphone 2 converting ultrasonic wave into electric energy, measured gas mixture consisting of two or more types of gases different in the ultrasonic wave sound speed is introduced. Further, ultrasonic wave transmission voltage is fed to the transmission side microphone 1 and the phase difference between transmission signal and reception signal of the gas mixture is read in by applying the ultrasonic wave transmission voltage to the transmission side microphone 1 and by use of the synchroscope connected to the reception side microphone 2. The quantitative analysis is made by comparing the phase difference with the estimate line showing the relation between the amount of measured gas contained and the phase difference made in advance.