When a mixture of powdered optically active host and racemic guest crystals is kept at room temperature, enantioselective transfer of guest molecule occurred from the racemic guest crystal to the host crystal and an inclusion crystal of the host and optically active guest molecules. When powdered inclusion crystal of an optically active host and a prochiral guest is mixed with powdered crystalline reagent and the mixture is kept at room temperature, enantioselective approach of the reagent to the prochiral Quest molecule was occurred and optically active product was obtained.