alpha-Aminophosphinic acid derivatives have been utilized as useful phosphinyl dipeptide isosteres (PDIs) for developing inhibitors against aspartic acid and Zn metallo proteases. We have established a new and efficient method for the synthesis of optically active aminomethylphosphinate bearing asymmetric center at phosphorus atom, which was an important starting compound for the preparation of PDIs. The method was based upon lipase-mediated kinetic resolution of a hydroxymethylphosphinate and its conversion into the corresponding amine derivative. This lipase-mediated acylation using vinyl acetate could be applicable to 10-gram scale giving 1.5-gram of hydroxymethylphosphinate with high optical purity (>99% ee).