To provide adhesives having biodegradability and transparency and strong adhesion to a substrate having silanol residues in its surface.

An adhesive for a substrate having silanol residues in its surface has, as the major component, a sugar chain polymeric compound represented by the formula, wherein G is a sugar residue; the hydroxyl groups in G which do not participate in polymerization may be substituted with an ester group; R is a 4-14C aliphatic hydrocarbon group or a 4-14C aliphatic hydrocarbon group whose hydrogen atom is substituted with another group; and n is a degree of polymerization and an integer of 1-5,000.