An optically active lactic acid derivative represented by the following formula (I): ##STR1## wherein R represents a linear, branched or cyclic saturated or unsaturated hydrocarbon group having 1 to 18 carbon atoms; C* represents an asymmetric carbon atom; l is 0 or 1; m is 1 or 2; A represents a group selected from the following groups (a) and (b):(a) hydroxyl group, halogen, benzyloxy group, phenoxy group, toluenesulfonic acid group, acetyloxy group, trifluoroacetyloxy group; ##STR2## (wherein R' is an alkyl group or alkoxy group having 4 to 18 carbon atoms, n is 0 or 1, ##STR3## with proviso that when A is selected from the groups in the above group (a), l is 1 and m is 1 or 2; and when A is selected from the groups in the above group (b), m=n=1 when l is 0, or m and n are 0, 1 or 2 and m+n is 1 or 2 when l is 1, and ##STR4##