A semiconductor manufacturing apparatus includes a processing chamber for performing a manufacturing processing on a wafer. A gas supply line for introducing a purge gas is connected to an upper portion of the processing chamber, a valve being installed on the gas supply line. A rough pumping line with a valve is connected to a lower portion of the processing chamber. Installed on the rough pumping line are a dry pump for exhausting a gas in the processing chamber and a particle monitoring unit for monitoring particles between the valve and the dry pump. In the semiconductor manufacturing apparatus, after the valve is opened, the purge gas is supplied to apply physical vibration due to shock wave in the processing chamber so that deposits are detached therefrom to be monitored as particles.