Efficient photoanodes of tungsten oxide (WO3) were fabricated on three-dimensional conductive carbon microfiber felts (CMFs). Monolayers of fine WO3 particles with a diameter of ca. 150 nm were successfully loaded on the surface of CMFs by simple impregnation of a mixed aqueous solution of ammonium metatungstate and poly(ethylene glycol) followed by calcination in air, affording higher photocurrent densities and IPCE values for water oxidation under visible light than those on a conventional porous WO3 electrode prepared on a conductive glass substrate.