The method for preparing an optically active (R)-amino compound characterized by the method comprising stereoselectively carrying out amino group transfer by action of an (R)-form-specific transaminase in the co-presence of a ketone compound (amino acceptor), and an amino compound (amino donor) of a racemic form or an (R)-form, to give an optically active (R)-amino compound. According to the present invention, it is made possible to easily prepare at a high yield the optically active (R)-amino compounds and the like having an aryl group and the like at their 1-position, which have been conventionally difficult to prepare.