A conjugated copolymer having an alternate structure of 9,10-diphenylanthracene and 1,3-diphenylallene was synthesized by the Suzuki-Miyaura cross-coupling reaction with 9,10-dibororanylanthracene and 1,3-bis(4-bromophenyl)-1,3-diphenylallene. The diphenylanthracene moiety worked as an absorptive and emissive center unit in the polymer. The twisted allene moiety not only controlled conjugation length of the polymer but also suppressed formation of excimers, which realized intense pure blue fluorescence with high quantum efficiency (Phi(f) approximate to 1.0) in CHCl3 solution.