The present invention relates to a method for producing N-protected amino acid. Specifically, the present invention provides a method in which a protecting group is introduced to the amino group of an amino acid in a reaction under alkaline condition, and the N-protected amino acid thus generated is then separated from the reaction solution as crystals, without undergoing an extraction step or a concentration step. The present inventors have completed the invention based on the finding that desirable crystals of N-protected amino acids may be obtained without extraction, concentration or recrystallization steps between the initial generation of the N-protected amino acid molecules and the subsequent separation of the crystals, by first adding an water-soluble organic solvent and optionally water to the reaction solution (alkaline) containing the N-protected amino acid, and then neutralizing the solution by an acid.