Abstract: L-aspartic acid is produced by repeating the following respective steps:(1) a reaction step of producing ammonium L-aspartate from an aqueous solution containing monoammonium maleate in accordance with an isomerization reaction and an enzyme reaction caused by aspartase in the presence of ammonia;(2) an ammonia-eliminating step of converting substantially all produced ammonium L-aspartate into monoammonium salt by distilling or stripping a reaction solution obtained in the step (1);(3) a crystallization step of crystallizing L-aspartic acid and producing monoammonium maleate from a solution obtained in the step (2) by adding maleic acid, maleic anhydride or both;(4) a solid-liquid separation step of separating L-aspartic acid crystals precipitated in the step (3) from a mother liquor containing monoammonium maleate; and(5) a recycle step of supplying the mother liquor containing monoammonium maleate obtained in the step (4) to the step (1) to be used as a raw material for the reaction.