A processing apparatus includes a process container having a placing table for placing a processing object, an exhaust system having vacuum pumps and a pressure control valve for exhausting atmosphere in the process container. A gas injection unit having a gas ejection hole is provided in the process container, as well as a gas supplying unit for supplying a process gas to the gas injection unit. The entire process apparatus is controlled by a controlling unit. The control unit controls the exhaust system and the gas supplying unit. When starting a predetermined process, the process gas at a flow rate greater than a prescribed flow rate is supplied for a short time while exhausting the atmosphere in the process container by the exhaust system, and then the process gas at a prescribed flow rate is supplied.