To provide a method for producing, in high yield, an optically active compound useful as an intermediate for medicines and agrochemicals and the like.

This optically active compound of formula (2) obtained by introducing a dihalomethy group with easily keeping a three-dimensional configuration can be produced by reacting a haloform CHX3 (X is a halogen) with an optically active compound of formula (1) in the presence of a phase transfer agent and a base. In the fomulas (1) and (2), R1, R2 are each a (aryl-, cyano-, amide-, alkoxy- or halogen-substituted) 1-10C alkyl, aryl or cycloalkyl; R3 is an alkylsilyl or a (aryl-, cyano-, amide-, alkoxy- or halogen-substitued) 1-10C alkyl, aryl or cycloakyl; R2 and R3 may form a ring together; R1, R2 and OR3 are not the same; and * denotes an asymmetric carbon.