A method for producing a solid electrolyte, comprising: grinding raw materials comprising lithium sulfide and phosphorus sulfide in a hydrocarbon solvent, optionally comprising stirring a slurry comprising the raw materials and the hydrocarbon solvent in a reaction vessel, and optionally, circulating the slurry through a connecting pipe, wherein the method is carried out in an apparatus comprising the grinder, the reaction vessel and the connecting pipe that connects the grinder and the reaction vessel.