A Rh-doped SrTiO3 (SrTiO3:Rh) photocatalyst electrode that was readily prepared by pasting SrTiO3:Rh powder onto a transparent indium tin oxide electrode gave a cathodic photocurrent under visible-light irradiation (λ > 420 nm), indicating that the SrTiO3:Rh photocatalyst electrode possessed p-type semiconductor character. The cathodic photocurrent increased with an increase in the amount of doped Rh up to 7 atom %. The incident-photon-to-current efficiency at 420 nm was 0.18% under an applied potential of −0.7 V vs Ag/AgCl for the SrTiO3:Rh(7 atom %) photocatalyst electrode. The photocurrent was confirmed to be due to water splitting by analyzing the evolved H2 and O2. The water splitting proceeded with the application of an external bias smaller than 1.23 V versus a Pt counter electrode under visible-light irradiation and also using a solar simulator, suggesting that solar energy conversion should be possible with the present photoelectrochemical water splitting.