NOVELTY - A fats-and-oil raw material contains free fatty acid in content more than setting amount. The fats-and-oil raw material containing free fatty acid in amount less than setting amount is subjected to transesterification with lower alcohol in presence of alkali catalyst. The fats-and-oil raw material containing free fatty acid in content more than setting amount is esterified, and the free fatty acid is esterified. The fatty-acid alkylester obtained by transesterification and/or esterification is subjected to fuel purification, to obtain biodiesel fuel.    USE - Manufacture of biodiesel fuel using fats-and-oil raw material such as animal fat and oil, vegetable oil, rapeseed oil, sesame oil, soy bean oil, corn oil, sunflower oil, palm oil, palm kernel oil, beef tallow and fish oil.    ADVANTAGE - The high-quality biodiesel fuel is manufactured efficiently and economically in high yield and even without causing environmental pollution.    DETAILED DESCRIPTION - A fats-and-oil raw material contains free fatty acid in content more than setting amount. The fats-and-oil raw material containing free fatty acid in amount less than setting amount is subjected to transesterification with lower alcohol in presence of alkali catalyst. The fats-and-oil raw material containing free fatty acid in content more than setting amount is subjected to esterification reaction, and the free fatty acid is esterified. The fatty-acid alkylester obtained by transesterification and/or esterification is subjected to fuel purification, to obtain biodiesel fuel. The free fatty acid produced in the distillation portion of transesterification, or glyceride unreacted substance produced during esterification is reused as fats-and-oil raw material. An INDEPENDENT CLAIM is included for apparatus used for producing biodiesel fuel, which comprises process selection portion, transesterification processing portion, esterification processing portion and fuel purifying portion. The process selection portion classifies the content of free fatty acid in fats-and-oil raw material in more than setting amount. The fuel purifying portion purifies fatty-acid alkylester obtained by transesterification and esterification.    DESCRIPTION OF DRAWING(S) - The drawing shows the flow sheet illustrating manufacturing process of biodiesel fuel. (Drawing includes non-English language text)