Calcinations of a tantalum-O-phenylene-O hybrid copolymer under an argon atmosphere have been found to give nano-sized tantalum oxide-carbon clusters composite material. ESR spectral examinations of the composite material suggest that the electron transfer from the tantalum oxide particles to the carbon clusters took place to raise a visible-light responsive function with an oxidation site in the tantalum oxide particle and a reduction site in the carbon cluster.