NOVELTY - Acidic oil and waste oil raw material are melted at 80 degrees C. Oil water slag is removed to produce refined acidic oil. The refined oil is heated at 180 degrees C for 2 hours, and hydrolyzed. Hydrolyzed fatty acid is supplied to esterification container. Methanol and tin oxide catalyst are added, heated to 90 degrees C and reacted for 2-3 hours. The fatty acid crude methyl ester is beaten in a neutralizing container and stirred for 10 minutes at 50 degrees C. The product is water-washed, and residual catalyst is removed. The resulting product is centrifuged and distilled to produce biodiesel.    USE - Manufacture of biodiesel.    ADVANTAGE - The biodiesel is economically manufactured.    DETAILED DESCRIPTION - Acidic oil and waste oil raw material are added to an oil melting pool, and melted at 80 degrees C. Oil water slag is removed to produce refined acidic oil. The refined oil is stored in a raw material storage tank. The raw material is pumped to a high-pressure hydrolysis container by a meter pump, and heated at 180 degrees C for 2 hours to hydrolyze the raw material into fatty acid. The hydrolyzed fatty acid is supplied to an esterification container by a meter pump. Methanol in an amount of 13 wt.% of fatty acid, and tin oxide catalyst in an amount of 1 wt.% of fatty acid are added and heated to 90 degrees C. The mixture is reacted for 2-3 hours at predetermined temperature and pressure. The reaction is completed, when the acidic value is less than 1. The obtained fatty acid crude methyl ester is beaten in a neutralizing container and stirred for 10 minutes with warm water at 50 degrees C. The product is water-washed and maintained for 3 hours to separate oil water residue, and residual catalyst is removed. The resulting product is centrifuged for dehydrating at a flow amount of 3 tons per hour to make the moisture of the dehydrated fatty acid crude methyl ester to less than 0.1%. The dehydrated material is supplied to a circulating distillation tower, in which the pressure is 0.5 kg. The temperature is controlled at 295 degrees C, and biodiesel is collected at 85-280 degrees C. The physical properties of biodiesel are detected, and stored. The small amount of oil slag at the bottom portion of the distillation tower during distillation is plant asphalt, which is used as fuel of boiler. Thus, biodiesel is produced.