According to the process for producing amino acid or salt thereof in the present invention, in the adsorption step, an amino acid-containing aqueous solution is fed into a pressure tight column so that a free amino acid is adsorbed on a carbonate-type anion exchange resin packed in the pressure tight column. Subsequently, in the elution step, eluent liquid containing a hydrogen carbonate ion and/or a carbonate ion is injected into the pressure tight column in a pressurized state to elute the amino acid adsorbed on the anion exchange resin and simultaneously to regenarate the anion exchange resin into the carbonate-type. In the case of purifying an acidic amino acid, an aqueous ammonium carbonate solution is employed as the eluent liquid. In the case of purifying a neutral amino acid, an aqueous carbonic acid solution, an aqueous hydrogen carbonate solution, an aqueous ammonium hydrogen carbonate solution or an aqueous ammonium carbonate solution is employed as the eluent liquid. Further, a breakthrough liquid discharged from the adsorption step is optionally concentrated to remove the volatile carbonate acid component and ammonium component from the breakthrough liquid. Thus, the solid content in the breakthrough liquid can be reduced.