PURPOSE: The titled optically active polymer having an optical rotatory power and being effective as an agent for use in optical resolution, resolution of geo- metrical isomers, etc., containing a specified methacrylate ester as a monomer for the main structural units.

CONSTITUTION: A halogen-containing organic copolymer based on the structural unit of formula III is obtained either by ion-polymerizing a methacrylate ester of formula I (wherein R1W3 are each a (substituted) aromatic group, and at least one of them is a halogen-containing phenyl of formula II, A is a halogen, preferably F, and p is the number of halogens and is 1W5) and, if necessary, other comonomers (e.g., triphenylmethyl methacrylate) in a solvent (e.g., toluene) in the presence of an alkyllithium catalyst at -98W60°C, or by ion-polymerizing the above monomer or monomers in the presence of an optically active anionic catalyst, e.g., lithium (R)-N-(1-phenylethyl) anilide.