An efficient BiVO ₄ thin film electrode for overall water splitting was prepared by dipping an F-doped SnO ₂ (FTO) substrate electrode in an aqueous nitric acid solution of Bi(NO ₃) ₃ and NH ₄VO ₃, and subsequently calcining it. X-ray diffraction of the BiVO ₄ thin film revealed that a photocatalytically active phase of scheelite-monoclinic BiVO ₄ was obtained. Scanning electron microscopy images showed that the surface of an FTO substrate was uniformly coated with the BiVO ₄ film with 300–400 nm of the thickness. The BiVO ₄ thin film electrode gave an excellent anodic photocurrent with 73% of an IPCE at 420 nm at 1.0 V vs. Ag/AgCl. Modification with CoO on the BiVO ₄ electrode improved the photoelectrochemical property. A photoelectrochemical cell consisting of the BiVO ₄ thin film electrode with and without CoO, and a Pt counter electrode was constructed for water splitting under visible light irradiation and simulated sunlight irradiation. Photocurrent due to water splitting to form H ₂ and O ₂ was confirmed with applying an external bias smaller than 1.23 V that is a theoretical voltage for electrolysis of water. Water splitting without applying external bias under visible light irradiation was demonstrated using a SrTiO ₃∶Rh photocathode and the BiVO ₄ photoanode.