The present invention provides a method for producing a compound represented by the formula (3): ##STR00001## wherein n is an integer of 1 to 6, characterized by the steps of hydrolyzing a solution containing an ester compound represented by the formula (1): ##STR00002## wherein R is a lower alkyl group and n is an integer of 1 to 6, and a compound represented by the formula (2): ##STR00003## wherein R is as defined above, adjusting the pH of the resulting solution to pH 4 to 8, and then subjecting to phase separation to obtain an organic layer containing the carboxylic acid of formula (3).