We have successfully synthesized a novel chiral AB block copolyacetylene consisting of a dynamic cis-transoidal racemic helical sequence and a static cis-cisoidal one-handed helical sequence by using a three step procedure, that is, synthesis of an achiral block copolymer by living polymerization of OH-protected monomers, deprotection of the resulting polymer, and selective chiral induction to that of the sequence.