The invention provides an optically active polymer which is a product obtained by polymerizing a chiral alkoxy-substituted phenylacetylene such as p-(2-methylbutoxy)phenylacetylene, of which the 2-methylbutoxy group has chirality, in an organic solvent such as triethylamine in the presence of a rhodium complex compound as a polymerization catalyst. The optically active polymer exhibits a much larger optical rotation than the monomeric compound per se and is colored in different colors of, e.g., yellow and black, depending on the organic solvent used for polymerization. The yellow polymer turns to black by exposure to the vapor of a specific organic solvent such as chloroform and returns to yellow by re-precipitation from a chloroform solution with addition of methyl alcohol as a precipitant.