NOVELTY - A fatty-acid-ester manufacturing apparatus has a decomposition reactor (A), a separator (B), a washing unit (C), and a reaction mechanism portion (D). Oil cake to which sulfuric acid is added is heated, stir-mixed, and decomposed. The separator separates acidulated soap stock containing fatty acid, and fats-and-oils produced by decomposition. The washing unit water-washes the stock, and the mixer (3c) in portion (D) mixes the stock with alcohol. The liquid mixture is supplied to portion (D) having a tubular reactor (4) for esterification.    USE - For manufacturing fatty acid ester for fuels (light oil alternate fuel, bio-diesel fuel).    ADVANTAGE - The apparatus enables efficient and economical manufacture of high purified fatty acid ester from oil cake, with high yield.    DETAILED DESCRIPTION - A fatty-acid-ester manufacturing apparatus has a decomposition reactor (A), a separator (B), a washing unit (C), and a reaction mechanism portion (D). The apparatus manufactures fatty acid ester from fatty-acid soap, fats-and-oils, water, and oil cake containing impurities. Oil cake to which sulfuric acid is added until pH becomes 5 or less, is heated at 50-120degreesC, stir-mixed, and decomposed in the decomposition reactor. The separator separates acidulated soap stock containing fatty acid, and fats-and-oils produced by decomposition from the reaction liquid in the decomposition reactor. The washing unit water-washes the acidulated soap stock, and the mixer (3c) in the reaction mechanism portion mixes the washed stock with 1-5C lower alcohol (0.5-1 weight times). The liquid mixture is supplied at a liquid space velocity of 0.08-0.13 l/minute to the reaction mechanism portion equipped with a tubular reactor (4) in which esterification is carried out under supercritical state of 200-350degreesC and 15-25 MPa pressure. The oil cake is obtained by de-oxidation process used for purifying fats-and-oils.    DESCRIPTION OF DRAWING(S) - The figure shows the manufacturing apparatus of fatty acid ester. (Drawing includes non-English language text)    Mixer (3c)    Tubular reactor (4)    Decomposition reactor (A)    Separator (B)    Washing unit (C)    Reaction mechanism portion (D)