TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: The setting amount of free fatty acid in the fats and oils raw material is 50 mass%. The solid substance and/or moisture content are removed beforehand from the raw material, by gravity separation. The free fatty acid is distilled from the raw material at 50-150degreesC under a reduced pressure of 10 mmHg or less. The free fatty acid in the distillation process is reused as raw material. The reaction liquid mixture obtained by transesterification is neutralized by adding a preset amount of dilute sulfuric acid and water, and is filtered to obtain sulfate crystals. The filtrate is distilled and fractionated to obtain a high density glycerol component. 1-20 mol equivalent of water is added during neutralization, w.r.t the amount of sulfate generated. 50 mass% or less of lower alcohol is added to the reaction mixed solution to adjust the viscosity at the time of neutralization. The lower alcohol is methyl alcohol. The alkali catalyst is potassium hydroxide. Esterification is performed by mixing an alcohol component with fats and oils raw material, pressurizing, heating to supercritical state of alcohol, and reacting such that the water is in dry vapor state. Distillation is performed and alcohol is fractionated. The acid value of the fatty acid alkyl ester obtained by esterification is less than 0.5. The fatty acid alkyl ester obtained by (trans)esterification is purified by centrifugation and gravity separation. The flow of fats and oils raw material in each process is performed continuously. EXAMPLE - Transesterification of yellow grease having an acid value of 18, a free fatty acid content of 9 mass%, a flash point of 238degreesC, a water content of 10 mass% and an ash content of 3.5 mass% was performed. Filtration was performed and the supernatant liquid was heated to 95degreesC. The raw material oil was centrifuged, heated to 145degreesC, introduced into a vacuum-deoxidation tower, distilled and cooled. A solution containing potassium hydroxide dissolved in methyl alcohol, was mixed with the raw material oil. Reaction was performed at 100 mmHg, and stirred for about 20 minutes at 65degreesC. The obtained product was separated as an alkyl ester layer and a glycerol layer, by centrifugation. The alkyl ester layer was passed through a column filled with activated clay, followed by centrifugation. A solid substance was separated and alkyl ester was filtered and purified. The yield of the end product was 99.5 mass% w.r.t glyceride derivative base. The free fatty acid recovery obtained from the vacuum-deoxidation tower was 97 mass%.