Processing gases respectively supplied from multiple gas supply lines into a processing vessel can be switched at a high speed in a uniform manner. A plasma processing apparatus includes the processing vessel configured to perform therein a plasma process to a target substrate; and a gas inlet member including first gas discharge holes and second gas discharge holes which are alternately arranged to be adjacent to each other and respectively communicate with a first gas supply line and a second gas supply line, which are switchable. Further, the first gas discharge holes and the second gas discharge holes independently and respectively introduce a first processing gas and a second processing gas, which are respectively supplied from the first gas supply line and the second gas supply line and used in the plasma process, into the processing vessel.