Uniformity of a process on a substrate is improved. A
plasma processing apparatus including a
processing container which is formed of
metal and receives a substrate to be
plasma-processed, an electromagnetic wave source which supplies an electromagnetic wave required to excite
plasma in the
processing container, and a plurality of dielectrics, through which the electromagnetic wave supplied from the electromagnetic wave source transmits to the inside of the processing container and which have a part that is exposed to the inside of the processing container, on a lower surface of a lid of the processing container, wherein a
metal electrode, which is electrically connected to the lid, is formed on a lower surface of each
dielectric, a part of each
dielectric exposed between the lower surface of the lid and the
metal electrode has a substantially polygonal outline when viewed from the inside of the processing container, the plurality of dielectrics are disposed with vertical angles of the polygonal outlines being adjacent to each other, and a
surface wave propagating portion, through which the electromagnetic wave is propagated, is formed on the lower surface of the lid exposed inside the processing container and a lower surface of the metal
electrode.