Abstract: A plasma processing apparatus has a vacuum container which contains a pair of electrodes for causing a discharge for generating a plasma, and a shielding plate for separating a plasma processing region including a space between the electrodes from a region in contact with the inner wall of the vacuum container in such a manner that both the regions communicate with each other. The apparatus includes a means for causing a pressure difference between the plasma processing region and the region in contact with the inner wall of the vacuum container.