A continuous process of amino acid concentration by a liquid emulsion membrane with a cation extractant, di-2-ethylhexyl phosphoric acid, was developed and optimized with respect to the yield of amino acid, the degree of concentration, and membrane stability. The liquid emulsion membrane obtained from demulsification of the emulsion could be reused without any problem. It was possible to concentrate the fermentation broth of initial concentration of 36 up to 170 g/l. A simple and continuous process was proposed to reduce the amino acid concentration of the fermentation broth down to 1.5 g/l.