NOVELTY - A polyanion-based positive electrode precursor is mixed with graphite oxide, to obtain precursor composite granules. The obtained precursor composite granules are heated, to obtain polyanion-based positive electrode composite particles. The maximum intensity of the X-ray diffraction peak based on the positive electrode active material is less than 50% of the maximum intensity of the X-ray diffraction peak based on the materials other than the positive electrode active material, with respect to the X-ray diffraction intensity of the precursor composite granules.    USE - Manufacture of polyanion-based positive electrode composite particles used as active material for lithium-ion secondary battery for electric vehicle and hybrid electric vehicle.    ADVANTAGE - The method enables manufacture of polyanion-based positive electrode composite particles having high electroconductivity and ionic conductivity. The high-power lithium-ion secondary battery obtained using polyanion-based positive electrode composite particles has high capacity.    DETAILED DESCRIPTION - A polyanion-based positive electrode precursor is mixed with graphite oxide, to obtain precursor composite granules. The obtained precursor composite granules are heated at more than 500 degrees C in inert atmosphere or reducing environment, to obtain polyanion-based positive electrode composite particles. The maximum intensity of the X-ray diffraction peak based on the positive electrode active material is less than 50% of the maximum intensity of the X-ray diffraction peak based on the materials other than the positive electrode active material, with respect to the X-ray diffraction intensity of the precursor composite granules. The maximum intensity of the X-ray diffraction peak based on the positive electrode active material is 50% or more of the maximum intensity of the X-ray diffraction peak based on the materials other than the positive electrode active material, with respect to the X-ray diffraction intensity of the polyanion-based positive electrode composite particles. An INDEPENDENT CLAIM is included for polyanion-based positive electrode precursor-graphite oxide composite granules.