PURPOSE: To provide a method for producing an N-alkoxycarbonylamino acid ester, capable of isolating the compound by a simple means from the reaction solution obtained by the reaction of an amino acid ester salt with a dicarbonate.

CONSTITUTION: When an N-alkoxycarbonylamino acid ester is produced by reacting an amino acid ester salt (but excluding hydrochloride) with a decarbonate of the formula (R1 is alkyl, alkenyl, aralkyl), the reaction is performed in the presence of an inorganic base, preferably a carbonic acid salt having a dehyration function, in an organic solvent slightly dissolving a salt produced by the neutralization of the inorganic salt in the reaction but capable of dissolving the produced objective compound. The organic solvent has a solubility of ≤1g/100 cc, especially ≤0.2g/100cc, for the salt, and a solubility of ≥10g/100cc, especially ≥30g/100cc, for the objective compound, and includes alcohols, ethers, nitriles, ketones, hydrocarbons, and chlorinated hydrocarbons.