A plasma processing apparatus includes a processing chamber arranged in a vacuum vessel. A wafer placed on a sample stage in the processing chamber is processed using a plasma formed in the processing chamber. Before etching the film layers provided on the wafer composed of a metal substance and an underlying oxide film or a material having a high dielectric constant, another wafer, provided on a surface thereof a film composed of a metal of the same kind as the metal substance, is processed and particles of the metal are deposited on an inner wall of said processing chamber.