A method applying a curable sealant composition comprising an oxyalkylene polymer having at least one silicon-containing group to the silicon atom of which a hydroxy group and/or a hydrolyzable group are bonded onto previously applied and cured sealant composition comprising an oxyalkylene polymer having at least one silicon-containing group to the silicon atom of which a hydroxy group and/or a hydrolyzable group are bonded, which method comprises applying a primer comprising a copolymer having at least one silicon-containing group to the silicon atom of which a hydroxy group and/or a hydrolyzable group are bonded,said copolymer having a molecular chain comprising substatially (1) a monomer unit of at least one of an alkyl acrylate and an alkyl methacrylate wherein the alkyl group has from 1 to 8 carbon atoms, and (2) a monomer unit of at least one of an alkyl acrylate and an alkyl methA method foracrylate wherein the alkyl group has not less than 10 carbon atoms, which method afford superior adhesiveness between previously applied sealant and newly applied sealant.