PURPOSE: To enable the reuse of an optically active amino acid derivative for industrially synthesizing a peptide by recovering the optically active amino acid derivative from a recovered liquid which has hitherto been discarded after synthetic reaction of the peptide in industrially synthesizing the peptide while retaining the optical activity thereof.

CONSTITUTION: This method for recovering an optically active amino acid derivative from a recovered liquid for an acyl component after use for synthetic reaction of a peptide is to add 1-hydroxybenzotriazole, 1-hydroxy-7- azabenzotriazole, 3-hydroxy-4-oxo-3,4-dihydro-1,2,3-benzotriazine or N-hydroxy-5- norbornene-2,3-dicarboximide in an equiv. amount of 5-20 times to the unreacted optically active amino acid derivative contained in the recovered liquid for the acyl component after use for the synthetic reaction of the peptide, concentrate the resultant mixture liquid, treat the residual material with a buffer solution at pH2-4 containing a tertiary amine and then extract the treated liquid under acidic conditions.