To provide a processing system capable of measuring an actual gas flow rate in a flow controller properly without generating a deficiency such as a damage or a corrosion in a flow measuring device.

This processing system comprises a processing device for introducing a processing gas into a processing vessel 8 through different flow controllers 38A-38E interposed in a gas introduction system, and the flow measuring device. In the system, the flow measuring device is equipped with an inspection vessel 54 having a prescribed capacity interposed in an inspection passage 52 for connecting the gas introduction system to a gas exhaust system, a pressure gage 58 for detecting the pressure in the inspection vessel, a flow operation part 64 for determining the gas flow rate in the flow controllers based on the rising speed of the detection value of the pressure gage, and a flow measuring control part 62 for controlling the whole operation at the flow measuring time. When feeding a prescribed processing gas into the inspection vessel, an inert gas is fed into the inspection vessel before or after feeding the processing gas, to thereby perform purge operation.