To provide an adhesive having a refractive index of 1.50 or greater and an adhesive force of 500 gf/25 mm or greater singly, and suitable for optical film adhesion such as for pressure-sensitive sheets, laminates or polarizing plates, and to provide a method for producing the adhesive.

The urethane resin adhesive is synthesized from raw materials comprising a hydroxyl-containing polyamino compound(E), a diisocyanate(B'), a diol(C) and a polyol(D). This adhesive has a refractive index of 1.50 or greater and has a linkage site represented by the formula(1): -R1-N(R3)-CO-NH-R2- and urethane groups. In the above formula(1), R1 is an amino group-bearing bivalent organic residue derived from the compound(E); R2 is a polyvalent organic residue derived from a polyisocyanate(B) formed after the polymerization of the compound(B'); and R3 is a monovalent organic residue containing at least one hydroxy group and derived from the compound(E).