NOVELTY - Raw material oil contains component oil in which glycerin and fatty acid are coupled. The fatty acid in raw material oil is methyl-esterified by reacting with methyl alcohol in presence of alkali catalyst. Then, light layer containing methyl-esterified fatty acid and heavy layer (A) containing fatty acid-separated glycerin are separated and heavy layer is removed, to obtain light layer. The separated light layer is washed. The impurity including water is removed by carrying out centrifugation process of cleaned light layer and filtered with filter, to obtain diesel fuel.    USE - Manufacture of diesel fuel (claimed) for e.g. biodiesel fuel.    ADVANTAGE - The method economically provides high quality diesel fuel in high yield by simple process.    DETAILED DESCRIPTION - Raw material oil contains component oil in which glycerin and fatty acid are coupled. The fatty acid in raw material oil is methyl-esterified by reacting with methyl alcohol in presence of alkali catalyst. Then, light layer containing methyl-esterified fatty acid and heavy layer (A) containing fatty acid-separated glycerin are separated and heavy layer is removed, to obtain light layer. The separated light layer is washed using wash water. The impurity including water is removed by carrying out centrifugation process of cleaned light layer and filtered with filter, to obtain diesel fuel. The washing process involves obtaining light layer by removing and cleaning heavy layer (B) including wash water, where vaporization removal of methyl alcohol is carried out by exceeding the boiling point of methyl alcohol and making light layer and wash water to appropriate temperature of less than the temperature in which light layer carries out bumping and separating cleaned light layer and heavy layer (B) including wash water.    DESCRIPTION OF DRAWING(S) - The drawing shows a block diagram illustrating manufacture of diesel fuel.    Raw material oil tank (2)    Reaction liquid tank (3)    Process tank (5)    Adjustment liquid tank (6)    Coagulant tank (7)    Flush tank (8)