PURPOSE: To easily obtain an optically active isomer of the titled ester derivative useful as a starting raw material for the production of insect pheromones and anti-inflammatory agents, by carrying out asymmetric hydrolysis of an α-hydroxycarboxylic acid ester derivative with a bacterial strain belonging to Corynebacterium genus.

CONSTITUTION: A bacterial strain belonging to Corynebacterium genus and capable of hydrolyzing an ester (e.g. Corynebacterium equi IFO 3730) is aerobically cultured in a medium containing an α-hydroxycarboxylic acid ester derivative of formula (R1 is lower alkyl, alkenyl, aryl or aralkyl; R2 is hydroxyl- protecting group; R3 is lower alkyl or aralkyl). The medium is preferably an inorganic salt medium containing a 14W20C olefin or saturated hydrocarbon.