A regio- and stereo-selective parallel synthesis of oligosaccharides on a solid support was successfully achieved by a combination of a novel α -selective glycosidation procedure and a uni-chemo hydroxyl protection (UCHP) procedure. The α -selective glycosidation of dibutyl 3,4-di- O -benzoyl-2,6-di- O -benzyl- α / β -D-galactopyranosyl phosphate in cyclopentyl methyl ether (as an ethereal solvent for effective swelling of the polystyrene resin) proceeded smoothly and in relatively high yield. Five types of trigalactoses [Gal α 1-3Gal β 1-3Gal, Gal β 1-3(Gal α 1-4)Gal, Gal α 1-4Gal β 1-3Gal, Gal α 1-3Gal β 1-4Gal, and Gal α 1-4Gal β 1-4Gal] were successfully synthesized on a solid support as a model of a combinatorial oligosaccharide library.