L-aminoacylases S.sub.1 and S.sub.2 derived from actinomycetes and having physicochemical characteristics such that it is a L-aminoacylase which acts on a N-acyl-L-amino acid to give a L-amino acid, its substrate profile is wide, and it acts not only on a N-acyl derivative of a natural L-amino acid, but also on a N-acyl derivative of a synthetic L-amino acid, while it does not act on a N-acyl-D-amino acid, a DL-N-acetyl-.alpha.methylbenzylamine and a N-acetyl-D-glucosamine, etc.