Abstract: Provided is a process for the preparation of an optically active (R)- or (S)-1-aminophosphonic acid derivative of the general formula (Ia) or (Ib) given below, which process comprises reacting an amino-protected imine having general formula (II): R.sup.1 --N.dbd.CHR.sup.2 where R.sup.1 is diphenylmethyl group or the like and R.sup.2 is an alkyl group or the like, with a phosphonic acid ester in the presence of an asymmetric catalyst consisting of a rare earth element-alkali metal-binaphthol complex, to produce an (R)- or (S)-N-protected-1-aminophosphonate compound, and then subjecting the phosphonate compound to catalytic reduction with hydrogen and to acidic hydrolysis. ##STR1## There are also provided novel intermediates, and a process of preparing an asymmetric catalyst consisting of a rare element-alkali metal-binaphthol complex.