Ca₃Co₄O₉ was synthesized by ultrasonic spray pyrolysis (USP) method. The concentration of metal ions in the starting solution was 0.1 mol/l or 0.01 mol/l as Ca₃Co₄O₉, and as the solvent, each of pure water, H₂O₂ solution or HNO₃ solution was used. The solution was sprayed in the furnace and pyrolyzed at 1073 K. X-ray powder diffraction analysis confirmed that all the powders prepared by USP were Ca-Co oxide. The powders were calcined at 1073 K and then sintered at 1173 K. The same sintering conditions were used for the powders prepared by the solid state reaction. The density of the sintered bodies prepared from USP powders ranged in 2.5-2.8gcm^-3 and they differed by the solvent of the starting solution. The density of the sintered bodies prepared by solid state reaction was higher than those by USP. The electrical conductivity of the sintered bodies prepared by USP ranged in 4700-5000 Sm^-1 at 1073 K, which was higher than those by solid state reaction. In contrast, Seebeck coefficient of the bodies prepared by USP was 106-108μVK^-1 at 1073 K, being smaller than those by solid state reaction.