PURPOSE: To obtain the titled cold curing composition, having characteristics of low modulus and high elongation and suitable as a filling material, etc., by blending a specific prepolymer with a caprolactone based polyol having a relatively low molecular weight as a crosslinking agent.

CONSTITUTION: The aimed composition obtained by blending a prepolymer, prepared from a high-molecular weight polyol (preferably triol having 3,000W8,000 average molecular weight) and an organic polyisocyanate (preferably 4,4'-diphenylmethane diisocyanate) and having terminal isocyanate groups with a caprolactone based polyol having a relatively low molecular weight (preferably 300W1,200 average molecular weight) as a crosslinking agent. Furthermore, the content of the isocyanate groups in the prepolymer is preferably 5W15wt.% and urethane elastomer has preferably ≤10kg/cm2 modulus at 100% and ≥700% tensile elongation.