Plasma processing device

An object of the invention is to suppress the diffusion of particles beyond the surface height of a substrate mounted on a mounting stage, while maintaining plasma stability. The invention provides a plasma processing device which performs plasma processing of a substrate by introducing gas into the interior of a reaction chamber where plasma processing is to be performed, and applying electromagnetic energy to the reaction chamber to generate a plasma from the gas, wherein the interior of the reaction chamber has a mounting stage on which the substrate is mounted, in this reaction chamber are formed a region A where a plasma is generated, an exhaust region Ex, and a region B which is located between the region A and the exhaust region Ex and in which a plasma is generated, the portions of the inside wall of the reaction chamber that adjoin the region A are formed from a vaporizable material, and a plurality of partition members formed from a vaporizable material are disposed downstream from the substrate sur