A plasma processing apparatus includes a gas ring forming a portion of a vacuum processing chamber and having a blowing port for a processing gas, a bell jar to define a vacuum processing chamber, an antenna for supplying an RF electric field into the vacuum processing chamber to form plasmas, a sample table, a Faraday shield, and a deposition preventive plate attached detachably at least to the inner surface of the gas ring excluding the blowing port. An area of the inner surface of the gas ring including the deposition preventive plate that can be viewed from the sample surface is set to about ½ or more of the area of the sample. A susceptor made of a dielectric material covers the outer surface and the outer lateral side of the sample table. A metal film is disposed with respect to the susceptor, and an RF voltage is applied to the metal film.