a plasma cvd device comprises a vacuum vessel that houses a discharge electrode plate and a ground electrode plate to which is attached a substrate for thin film formation . the plasma cvd device has an earth cover at an interval from and facing the aforementioned discharge electrode plate ; the aforementioned discharge electrode plate has gas inlets and exhaust outlets that are connected at one end to equipment supplying raw gas for thin film formation and that open at the other end at the bottom face of the aforementioned discharge electrode plate ; the aforementioned earth cover has second gas inlets corresponding to the aforementioned gas inlets , and second exhaust outlets corresponding to the aforementioned exhaust outlets . the plasma cvd device has an electric potential control plate disposed at an interval from and facing the aforementioned ground cover .