Abstract: An object is to make it possible to prevent electron temperature distribution from becoming uneven at surface of a process object when dimensions of the process object are large. A region division unit 30 encloses the inside of a ring-shaped discharge electrode 15 in the vicinity of that discharge electrode 15, thereby dividing the interior region of a tube-shaped vacuum vessel 11 in a direction perpendicular to the center axis Z thereof into a plasma generation region R1 and a plasma diffusion region R2, This region division unit 30 has a tube-shaped grid 301. This grid 301 has a plurality of electron passing holes and exhibits electrical conductivity. This grid 301, furthermore, is set in place concentrically with the vacuum vessel 11 so as to be positioned on the outside of a substrate W.