A metal-containing film can be formed with high continuity with respect to a base when forming the metal-containing film on the base by CVD or ALD. A film forming method of forming, by ALD or CVD, a Ti-containing film on a base film of a processing target object having a SiO2 film as the base film includes performing a surface processing of accelerating formation of a silanol group on a surface of the SiO2 film by bringing a fluid containing O and H into contact with the surface of the SiO2 film; and performing a film forming processing of forming the Ti-containing film on the SiO2 film, on which the surface processing is performed, by the ALD or the CVD with a Ti source gas which reacts with the silanol group.