PURPOSE: The titled composition having a pendant ethylenically unsaturated group in the polymer part and being useful as a material for polyurethane, obtained by polymerizing a polyol with a specified ethylenically unsaturated monomer.

CONSTITUTION: The titled ethylenically unsaturated group-containing composition is obtained by polymerizing 5W400pts.wt. ethylenically unsaturated monomer (A) comprising 5W95wt% at least one diene monomer (e.g., dicyclopentadiene) selected from among a condensed alicyclic nonconjugated diene compound, a bridged alicyclic nonconjugated diene compound and a linear nonconjugated diene compound having one α-olefinic bond, represented by the formula (wherein R1 and R2 are each H or a 1W4C alkyl, R3 is 2W10C alkyl and R4 is a 1W4C alkyl), 5W95wt% (meth)acrylonitrile and 0W80wt% other ethylenically unsaturated monomers (e.g., styrene) is polymerized with 100pts.wt. polyol (B) (e.g., polyether polyol) at 60W180°C to a conversion to polymer of 5W70wt%.