A plasma processing apparatus includes a processing chamber, a stage, a dielectric member, a microwave introduction device, an injector, and an electric field shield. The processing chamber has a processing space therein. The stage is provided within the processing chamber. The dielectric member has a through hole and is provided to face the stage. The microwave introduction device is configured to introduce microwave into the processing space via the dielectric member. The injector has at least one through hole and is made of a dielectric material, e.g., a bulk dielectric material. The injector is provided within the dielectric member. The injector and the through hole of the dielectric member form a path for supplying a processing gas into the processing space. The electric field shield encloses the injector.