PURPOSE: To prepare the titled chain polymer having high molecular weight, useful as a separation membrane and electronic materials, etc., in high conversion, in a short time, by polymerizing 1-bromo-2-phenyl acetylene compound using a catalyst containing a compound of the VI-group transition metal of the periodic table, etc.

CONSTITUTION: The objective polymer is prepared by polymerizing the 1-bromo- 2-phenylacetylene compound of formula (A is halogen, 1W10C alkyl, aralkyl, alkoxy, or aryloxy; n is 0W5) using a catalyst comprising preferably 0.5W5mol% of a VI-group transition metal compound (e.g. chloride or carbonyl compound of molybdenum, tungsten, chromium, etc., preferably molybdenum pentachloride) and if necessary an organometallic compound (preferably a compound of tin, silicon or bismuth, and the molar ratio of the compound to the transition metal chloride is 1).