PURPOSE: To purify a cyclic olefin containing impurities into a purified product having industrially sufficient polymerization activity by bringing a cyclic olefin containing impurities into contact with a basic aqueous solution and to successively polymerize the purified product in high yield by using a specific catalyst.

CONSTITUTION: (A) A cyclic olefin containing impurities is brought into contact with (B) a basic aqueous solution such as an aqueous solution of an alkaline (earth) metal hydroxide or (hydrogen)carbonate to purify the component A and optionally successively, the cyclic olefin phase obtained by the purification is polymerized in the presence of (C) a metallocene compound of the formula (M is Ti, Zr or Hf; A is a mononuclear or polynuclear hydrocarbon group; R1 is a disubstituted silylene by a 1-4C alkylene, a 1-6C alkyl or a 6-13C aryl; R2 and R3 are each a halogen, a 1-6C alkyl or a 6-13C aryl).