A plasma film forming apparatus comprises gas supply means for feeding a processing gas into a processing chamber, a first electrode opposed to an object of processing in the processing chamber, a second electrode in the form of a flat coil facing the first electrode across the object of processing, pressure regulating means for keeping the pressure in the processing chamber at 0.1 Torr or below, heating means for heating the object of processing to a predetermined temperature, and application means for applying radio-frequency power between the first and second electrodes, whereby the processing gas is converted into a plasma such that a film is formed on the surface of the object of processing through reaction of ions or active seeds in the plasma. When radio-frequency power is applied between the pair of electrodes, a radio-frequency electric field is formed. Since one of the electrodes is the flat coil, however, a magnetic field is formed. As a result, the processing gas is converted into a plasma by electrical and magnetic energies. Accordingly, the processing gas can be changed into a plasma under low pressure, and a high-density plasma can be generated even under a pressure of 0.1 Torr or below. Thus, the efficiency of ion application to the surface of the object of processing is high, and the effect of impurity extraction is great.