The first aspect of the present invention provides a method of manufacturing an active material capable of improving the discharge capacity of a lithium-ion secondary battery. The method of manufacturing an active material in accordance with the first aspect of the present invention comprises the steps of heating a phosphate source, a vanadium source, and water so as to form an intermediate containing phosphorus and vanadium and having a specific surface area of at least 0.1 m2/g but less than 25 m2/g; and heating the intermediate, a water-soluble lithium salt, and water. The second aspect of the present invention provides a method of manufacturing an active material capable of improving the rate characteristic of a lithium-ion secondary battery. The method of manufacturing an active material in accordance with the second aspect of the present invention comprises the steps of heating a phosphate source, a vanadium source, a water-soluble organic compound, and water for 1 to 12 hr so as to form an intermediate; and heating the intermediate, a lithium salt, and water.