PURPOSE: To save the power and the carrier gas without lowering the analyzing efficiency, by supplying the operational powers for gas chromatograph and mass spectrograph in time sharing by means of timers.

CONSTITUTION: Timers 12, 13 are connected to a power sources 12, 13 where the power source 4 for gas chromatograph, heater power source 5 for mass spectrograph and a power source 6 for an electromagnet are connected to the timer 12 to operate a gas chromatograph 8 and a mass spectrograph 9 thus to operate the valve 12 for carrier gas cylinder 11. Furthermore an exhaust system 10 for the mass spectrograph is connected through an exhaust sequencer 7 to the timer 3. Consequently the timers 2, 3 can be set to automatically stop the system under nonmeasuring state in the night while to restart automatically when measuring, thereby the consumption of the power and the carrier gas can be reduced to achieve the energy saving.