An improved, low porosity, solid electrolyte membrane and a method of manufacturing the solid electrolyte membrane are provided. The low porosity, solid electrolyte membrane significantly improves both mechanical strength and porosity of the membrane, inhibits the growth of lithium dendrites (Li dendrites), and thereby maintains and maximizes electrochemical stability of an all-solid-state battery. This is accomplished by wet-coating a sulfide or oxide solid electrolyte particle with a thermoplastic resin, or a mixture of the thermoplastic resin and a thermosetting resin, using a solvent to prepare a composite and hot-pressing the composite at a relatively low temperature and at a low pressure.