A polyurethane resin which is formed by reaction of a polyol with a curing agent comprising a trimer of aliphatic diisocyanate or of alicyclic diisocyanate, and lysine triisocyanate represented by the formula below. <IMG> The polyurethane resin is of non-yellowing type and superior in quick-curing properties, flexibility, and impact resistance. It is useful as a coating material for automobiles and building external finishing which needs good scratch resistance and chipping resistance.