To produce a film having good quality at high film-forming speed by introducing mixed gas of a carrier gas and oxygen to near a target and sputtering, simultaneously, activating and discharging mixed gas of component gas and the carrier gas in a qualtz tube arranged in a non-erosion area at the center part of the target with a magnetron discharge and reacting with the oxygen near the target.

Ar and SiCl4 introduced into the qualtz tube 3 from an introducing hole 3b are excited and activated with magnetic field developed by giving high frequency induction field to an excitation coil 4. The mixed gas of Ar and O2 is introduced to near the target 2 composed of SiO2 and the electric power is supplied to the target 2 to execute the sputtering, and simultaneously, the activated Ar and SiCl4 gas in the qualtz tube 3 is introduced from a discharging hole 3a and reacted with O2 to form an SiO2 film on a substrate 1. The film-forming speed several times faster than the film-forming speed with only the sputtering, is obtd. The film-forming speed related to TiO2 film and Al2O3 film is similar to the film forming speed of the SiO2 film.