A method of producing reduced glutathione by electrolytic reduction of oxidized glutathione using a cathode cell and an anode cell separated from each other by a separating membrane, including using a cathode having a metal cathode surface, and, as a cathode solution, an aqueous oxidized glutathione solution having a pH adjusted to higher than 3.0 and 5.0 or below by adding a base, which is added with the same metal as the metal of the cathode surface, a metal salt thereof, or a metal oxide thereof.