To produce an optically active primary amine useful as a chiral building block of intermediates for optically active medicines or agrochemicals, optical resolving agents and asymmetric synthetic catalysts.

A mixture of an optically active substance having carbonyl group [e.g. (-)-menthone] is reacted with a mixture of the (r)-isomer with the (s)-isomer of a primary amine having an optically active site (e.g. phenylethylamine) in the presence of a Lewis acid catalyst (e.g. a zinc halide) to afford an optically active amine derivative. When the optically active primary amine is reacted with the optically active substance having the carbonyl group, Schiff bases are formed and the resultant two kinds of diastereomers are then hydrolyzed to afford a primary amine having the optical activity improved as compared with that of the starting raw material. The Lewis acid is used to coordinate with the optically active substance having the carbonyl group and extremely great stereoregulation is imparted to the reactional system when reacting the primary amine therewith. Thereby, the optical activity derived from the primary amine is improved.