A process for producing a 2-alkylcysteinamide, which comprises hydrolysis of a 4-alkylthiazolidine-4-carboxamide represented by the general formula (2) or a salt thereof: ##STR00001## wherein R represents a lower alkyl group having 1 4 carbon atoms; and each of R.sub.1 and R.sub.2 independently represents hydrogen or a lower alkyl group having 1 4 carbon atoms, or R.sub.1 and R.sub.2 are linked together to form an alicyclic, structure having 4 7 carbon atoms, excluding the case where both R.sub.1 and R.sub.2 are hydrogen, to give a 2-alkylcysteinamide represented by the general formula (1) or a salt thereof ##STR00002## wherein R represents a lower alkyl group having 1 4 carbon atoms.Cells of a microorganism or treated products thereof having activity of stereoselective hydrolysis of a 2-alkyl-L-cysteinamide are allowed to act on the compound represented by the general formula (1) to yield a 2-alkyl-L-cysteine.