The elution behaviors of the rare earths was carried out in the iminodiacetic acid solution of various pH as eluent using ion exchange resin. The optimum eluent for the quantitative separation of $Eu^{3+},;Pr^{3+},;Ce^{3+};and;La^{3+}$ were 0.0301M IMDA solution of pH 8.00 and 9.00 at 5cm column of the resin Dowex 50${ imes}$8 (100-200 mesh). The elution order of the rare earth elements was in order of the atomic number of those elements. From the elution behavior of rare earth and u.v spectrum we found that the complexed rare earth species with IMDA changed according to pH of IMDA.