Abstract: A plasma processing apparatus includes a table (22) on which a processing target (W) is to be placed, a processing vessel (11) where the table is to be accommodated, and a power feed unit (40) for supplying a high-frequency electromagnetic field (F) into the processing vessel. The power supply unit includes at least a cylindrical waveguide (41) for introducing the high-frequency electromagnetic field, and a circular polarization antenna (51) arranged at one end of the cylindrical waveguide to supply the high-frequency electromagnetic field as a rotating electromagnetic field rotating in a plane perpendicular to its traveling direction. Accordingly, there is no need of providing a circular polarization converter for converting the high-frequency electromagnetic field in the cylindrical waveguide into the rotating electromagnetic field.