Electrochemical behavior of two block copolypeptides consisting of poly(L-2-anthraquinonylalanine) unit as a component was studied with voltammetric analyses and electrochemical spectroscopy. Cyclic voltammetry and differential pulse voltammetry indicated that the anthraquinonyl groups in the polypeptides show only the first redox wave at the potential that corresponds to the monoanion formation of monomeric compounds. Under the same conditions monomeric compounds showed both the first and second redox waves. Absorption spectra under constant electric potential indicated that anthraquinone dianions are formed in the polypeptides under potentials where monoanions are formed in the monomeric compounds. The result indicates that dianions are more stable than monoanions in the polypeptides. The mechanism of dianion formation was tentatively attributed to fast electron migrations among anthraquinonyl side groups of the polypeptides, followed by efficient disproportionations. CD spectroscopy indicated that no conformational change is associated with the redox processes. These unique properties suggest that poly(anthraquinonylalanine) is a promising candidate for a helical molecular wire that mediates electrons between electrodes and redox enzymes.