To obtain the subject oligosaccharide such as a ligand sugar chain bindable to cell adhesion molecule, by making a sulfotransferase having activity to transfer a sulfate group to a specific site of the galactose residue in a lactosamine oligosaccharide act on a lactosamine oligosaccharide.

A sulfotransferase (e.g. chondroitin 6-sulfotransferase) having activity to transfer a sulfate group to the 6-site of the galactose residue in a lactosamine oligosaccharide is made to act, in the presence of adenosine 3'-phosphate 5'-phosphosulfate, on a lactosamine oligosaccharide expressed by e.g. formula I (Gal is galactose residue; GlcNAc is N-acetylglucosamine residue; R is H or a 1-17-ose sugar chain) to obtain the objective sulfated lactosamine oligosaccharide expressed by e.g. formula II [(6S) means that 6-site lies sulfated] and playing a part in intercellular adhesion as a ligand sugar chain bindable to cell adhesion molecule belonging to the selektin family.