A cold storage box 1 comprises a housing 2 internally having a storage space S for a cold storage object, and one or more heat exchanger tubes 3 provided in the storage space S; wherein the heat exchanger tubes 3 are each a multilayer tube comprising an outer tube with thermal conductivity having an outer surface facing the storage space S, and as inner tube provided inside the outer tube; a first brine solution that does not freeze at 0° C. is contained between the outer tube and the inner tube; and a refrigerant, or a second brine solution that does not freeze at 0° C. is contained inside the inner tube.