Provided is a substrate processing device comprising an anode unit (17) that includes a first plate (23) and a second plate (24). The first plate (23) includes a plurality of first through-holes (23a), and by causing a gas to flow through the first through-holes, causes the gas to diffuse in the direction of the surface of the first plate (23). The second plate (24) includes a plurality of second through-holes (24a) that are larger than the first through-holes (23a). The second plate (24) causes the gas that has passed through the first through-holes (23a) to flow between the second plate (24) and a cathode stage through the plurality of second through-holes (24a). The second through-holes (24a) have a shape such that the emission intensity of plasma inside each second through-hole can be made higher than the emission intensity of plasma generated between the second plate (24) and the cathode stage.
