The present invention provides a particle measuring system which is provided in a processing system 40 which generates an atmosphere obtained by exhausting air or a gas in a processing chamber 48 by a vacuum pump 98 and applies a process concerning semiconductor manufacture to a wafer W in the atmosphere, attached to an exhaust pipe 90 which connects an exhaust opening 86 of the processing chamber 48 with the vacuum pump 98, and measures the number of the particles in the exhaust gas, and a measuring method thereof, the system and method providing a processing system and a cleaning method which terminate etching process by determining an end point based on the number of the particles in the exhaust gas and perform cleaning of unnecessary films.