PURPOSE:To increase the film forming rate on a substrate and to suppress the generation of dust by setting the substrate on an anode, incorporating a magnet into a cathode to form a magnetic field in its vicinity, and producing plasma between both electrodes under specified pressure. CONSTITUTION:The cylindrical drum substrate 2 is set on the anode (not shown in the figure) in a vacuum chamber 1, two-piece semicircular RF electrodes 3a and 3b are arranged as the cathode around the substrate 2 apart from each other. Gas inlet pipes 4a and 4b are connected to the RF electrodes 3a and 3b, raw gases introduced from the pipes 4a and 4b are supplied to a space between both electrodes from nozzles 7 pierced with many holes through gas passages 6. Glow discharge is generated from both electrodes to produce plasma between both electrodes, and a thin film is formed on the surface of the substrate 2. In the plasma CVD device, the magnets 5 are incorporated in the RF electrodes 3a and 3b as the cathode to generate a magnetic field in the vicinity of the inner peripheries. In addition, the inside of the vacuum vessel 1 is evacuated to <=0.1Torr, or preferably to <=about 0.05Torr. By this method, the plasma is highly densified, and polymerization is reduced.