In one embodiment, a fine-dispersion compounding apparatus includes a closed container into which solid material is fed; a boiler configured to introduce high-pressure steam into inside of the closed container; a rotating body configured to knead the solid material with liquid medium generated from condensed high-pressure steam by rotating inside the closed container; an open port configured to set internal pressure of the closed container to atmospheric pressure level by releasing a closed state of the closed container; a conveying port configured to convey kneaded mixture of the solid material and liquid medium from inside to outside of the closed container; a mixed dispersion unit configured to disperse the conveyed kneaded mixture and compounding material; a liquid-medium ejection unit configured to eject the liquid medium contained in the kneaded mixture; and an extraction unit configured to extract a composite compound of the compounding material and the solid material.