There is provided a technique that includes: (a) modifying a surface of a first base exposed on a surface of substrate by supplying modifying gas to the substrate including the first base and a second base exposed on the surface of the substrate; (b) selectively forming a first film on a surface of the second base by supplying first film-forming gas to the substrate after performing (a); (c) etching the first film formed on the surface of the first base to expose the surface of the first base and remodifying the surface of the first base by supplying first fluorine-containing gas to the substrate after the first film is formed on the surface of the first base after performing (b); and (d) selectively forming a second film on the first film formed on the surface of the second base by supplying second film-forming gas to the substrate after performing (c).