To realize a high productivity while maintaining excellent film deposition characteristics on a substrate even if a plurality of processing gases of different gas species are used. There are provided the step of loading a plurality of substrates into a processing chamber; supplying a first processing gas to an upper stream side of a gas flow outside of a region where a plurality of substrates loaded into a processing chamber are arranged, supplying a second processing gas to the upper stream side of the gas flow outside of the region where the plurality of substrates loaded into the processing chamber are arranged, supplying the first processing gas to a middle part of the gas flow in the region where the plurality of substrates loaded into the processing chamber are arranged, and causing the first processing gas and the second processing gas to react with each other in the processing chamber, to form an amorphous material and form a thin film on main surfaces of the plurality of substrates; and the step of unloading the substrate after forming the thin film from the processing camber.