A thin-film forming method comprising an uncured-layer forming step in which a mixed composition containing an organic polymerizing agent curable composition and a silicone polymerizing curable composition is prepared to form an uncured layer consisting of this mixed composition on a resin substrate; a solvent removing step in which the solvent in the uncured layer is removed; a first polymerization curing step in which the organic polymerizing curable composition in the uncured layer is polymerized; and a second polymerization curing step in which the silicone polymerizing curable composition in the uncured layer is polymerized. The thin-film forming method can comprise formation of the uncured layer on a resin substrate through the intermediation of a primer layer or formation of an uncured underlayer and uncured top layer followed by separate underlayer polymerization and top layer polymerization curing steps. The methods are applicable to the production of abrasion-resistant and water-repellent resin glass for automobiles.