A novel achiral phenylacetylene having a bulky t-butyl group was synthesized and polymerized by a chiral catalytic system containing [Rh(nbd)Cl](2) (nbd: norbomadiene) and chiral amines to yield a one-handed helical polymer having a much higher g value than polymers with no bulky groups. Highly efficient helix-sense-selective polymerization has been achieved using a bulky monomer and a less bulky chiral cocatalyst.