Capsinoids of formula (3) may be conveniently prepared in a high yield, in a short time, without using a dehydrating agent by esterification of a fatty acid of formula (1) with a hydroxymethylphenol of formula (2) using an enzyme without a solvent or in a low-polar solvent. Addition of a fatty acid represented by formula (4) is effective for stabilizing the ester compound of formula (3). ##STR00001## wherein each symbol is as defined in the specification.