TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Particle: The synthetic fine particle is perovskite-type oxide. The fine particle contains one or more types of metallic element chosen from rare earth element, metallic element(s) chosen from alkali metal of lithium, sodium and potassium, metallic element(s) chosen from alkaline earth metal of barium, magnesium, calcium and strontium, and two or more metallic elements chosen from transition metal of chromium, manganese, iron, cobalt, nickel, titanium, vanadium, germanium, copper, zirconium, lead, tungsten, antimony, bismuth, zinc and niobium. The synthetic fine particle is heat-processed.Preferred Method: Mechanical force is provided with respect to the fine particle between the deposition surface (3a) on which the fine particle is deposited, and processing surface (5a), by relatively moving the processing surface. The processing surface is arranged opposite to the deposition surface and slides in convex shape along the deposition surface.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Particle: The synthetic fine particle is perovskite-type oxide. The fine particle contains one or more types of metallic element chosen from rare earth element, metallic element(s) chosen from alkali metal of lithium, sodium and potassium, metallic element(s) chosen from alkaline earth metal of barium, magnesium, calcium and strontium, and two or more metallic elements chosen from transition metal of chromium, manganese, iron, cobalt, nickel, titanium, vanadium, germanium, copper, zirconium, lead, tungsten, antimony, bismuth, zinc and niobium. The synthetic fine particle is heat-processed.Preferred Method: Mechanical force is provided with respect to the fine particle between the deposition surface (3a) on which the fine particle is deposited, and processing surface (5a), by relatively moving the processing surface. The processing surface is arranged opposite to the deposition surface and slides in convex shape along the deposition surface. EXAMPLE - Lanthanum trioxide (La2O3) fine particle, manganic oxide (Mn2O3) fine particle and strontium carbonate (SrCO3) fine particle, were mixed, and a raw material was prepared. Subsequently, the fine particle raw material was ground by applying compressive force and shear force under dried condition, and synthetic fine particle of lanthanum-strontium-manganese oxide (La(Sr)MnO3) was produced.    The obtained synthetic fine particle of lanthanum-strontium-manganese oxide had Brunauer Emmett Teller (BET) specific surface area of 7.1 m2/g and calculated particle diameter of 150 nm.