PURPOSE: To obtain a composition having high practical value and capable of giving an RIM urethane having excellent rigidity and impact resistance or a soft foam having high hardness and high elasticity, etc., by polymerizing a specific ethylenic unsaturated monomer dispersed in a polyol.

CONSTITUTION: The composition is composed of a polymer prepared by polymerizing a polyol and an ethylenic unsaturated monomer (at least a part thereof is cyclic hydrocarbon diene monomer containing ethylidene group) dispersed in the polyol. The ethylenic unsaturated monomer is a mixture of 5W95(wt)% cyclic hydrocarbon diene monomer containing ethylidene group, 5W95% acrylonitrile or methacrylonitrile, and 0W80% other ethylenic unsaturated monomer. The polyol is polyether polyol. A polyurethane is produced by reacting the polymeric polyol composition with a polyisocyanate.