Helical peptides carrying naphthyl groups at the side chains and a ferrocene unit at the C terminal were self-assembled on gold, and photocurrent generation upon photoexcitation of the naphthyl groups was studied in an aqueous solution containing an electron donor. The ferrocene unit is found to promote photocurrent generation when it has an appropriate oxidation potential to act as an electron hopping site between the naphthyl group and the aqueous donor.