CYCLOOLEFIN-BASED RUBBER AND PROCESS FOR PRODUCING SAME, RUBBER COMPOSITION, CROSSLINKED RUBBER OBJECT, AND TIRE

A cycloolefin rubber having a weight average molecular weight of 100,000 to 800,000, having a silyl group at the polymer chain end, and containing a fatty acid ester of a polyvalent alcohol is provided. According to the present invention, a cycloolefin rubber excellent in processability at the time of blending and kneading and excellent in low heat buildup property can be provided.