An asparagine-linked .alpha.2,3-oligosaccharide having undeca- to hepta-saccharides, an asparagine-linked .alpha.2,6-oligosaccharide having undeca- to hepta-saccharides and containing fluorine and an asparagine-linked oligosaccharide derivative containing at least one fucose in N-acetylglucosamine on the nonreducing terminal side of an asparagine-linked oligosaccharide wherein the asparagine has amino group protected with a lipophilic protective group, and a process for producing these compounds.