In a plasma processing apparatus provided with control means, gas supply means includes a first gas supply path for supplying a vent gas into a processing chamber by way of a shower plate and a second gas supply path for supplying a vent gas into the processing chamber without via the shower plate, and the control means is capable of adjusting a flow rate of the vent gas of at least one of the first and second gas supply paths in such a manner that a pressure on a back side of the shower plate becomes a pressure that is a positive pressure relative to a pressure in the processing chamber and less than a withstand pressure of the shower plate.