A method for producing an optically active compound comprising:a first step of culturing a microorganism capable of assimilating either the R-isomer or the S-isomer of a compound represented by Formula (1): ##STR00001## wherein R is a methyl, ethyl, propyl, chloromethyl, or hydroxyethyl group, in a culture medium whose Ca.sup.2+ concentration at the beginning of culturing is controlled and which contains a racemic mixture of the compound as a carbon source; and a second step of recovering the optically active compound remaining in the culture broth.