A plasma processing apparatus includes an evacuatable processing vessel; a workpiece mount base for mounting thereon an object to be processed; a microwave transmitting plate provided in an opening of a ceiling of the processing vessel; a planar antenna member for supplying a microwave into the processing vessel via the microwave transmitting plate; a shield lid grounded to cover a top of the planar antenna member; a waveguide for guiding the microwave to the planar antenna member; a member elevating mechanism for relatively varying a vertical distance between the planar antenna member and the shield lid; a tuning rod insertable into the waveguide; a tuning rod driving mechanism for moving the tuning rod to adjust an insert amount thereof; and a matching control section for controlling an elevation amount of the planar antenna member and the insert amount of the tuning rod to obtain a matching adjustment.