A process for easily producing an optically active .beta.-amino alcohol useful as a pharmaceutical intermediate from an inexpensive, readily available starting material is provided. A readily available .alpha.-substituted ketone is reacted with an optically active amine to yield a diastereomer mixture of an optically active .alpha.-substituted aminoketone. One of the diastereomers is isolated optionally after the diastereomers are converted to salts with an acid. The optically active .alpha.-substituted aminoketone or a salt thereof thus isolated was stereoselectively reduced to yield an optically active .beta.-substituted amino alcohol. The optically active .beta.-substituted amino alcohol is subjected to hydrogenolysis to produce an optically active .beta.-amino alcohol or a salt thereof.