The present invention provides a method for producing a
fatty acid ester inexpensively and efficiently by reacting a
lipase or an intact mircroorganism containing a
lipase, an oil and fat, and a linear lower
alcohol in a
system containing little or no
solvent in the presence of water. The intact
microorganism has not been treated with a
solvent or the like, and is used as such, so that a
fatty acid ester can be prepared in a simple manner. An oil and fat, a natural oil and fat such as a
vegetable oil and fat, an
animal oil and fat, as well as a
waste oil thereof can be used. According to the method of the present invention, a reaction proceeds even in the presence of water, so that waste oils containing a large amount of water can be used as a
raw material. Therefore, the
waste oil to be dumped into the environment can be recycled, and a
biodiesel fuel, which hardly pollutes the environment, can be provided at the same time.