NOVELTY - The apparatus (1) has a grinder for grinding the raw material in a solvent. A main circulation path (A) consists of a second connection pipe (40) which connects the first connection pipe (30) that connects the exit of the grinder, the inlet port of a reaction tank (20), and the inlet port of the grinder. A sub circulation path (B) consists of the connection device (100) which connects the exit and inlet port of the reaction tank. The main and sub circulation paths share the path in the exit of the reaction tank.    USE - Apparatus for manufacturing solid electrolyte used for lithium secondary battery. Uses include but are not limited to two-wheeled motor vehicle, electric vehicle, hybrid electric vehicle, portable information terminal, portable electronic device and domestic-use electric power storage apparatus.    ADVANTAGE - The obstruction of the grinder is prevented, and the solid electrolyte is manufactured stably.    DETAILED DESCRIPTION - The lithium sulfide, phosphorus sulfide, sulfuration silicon, sulfuration boron, and germanium sulfide are contained in raw material. A reaction tank synthesizes the solid electrolyte by the reaction of lithium sulfide with other sulfide in raw material of solvent. The sub circulation path shares the portion of the main circulation path with first connection pipe. The pumps (46,104) make the main circulation path and sub circulation path common. An INDEPENDENT CLAIM is included for a method of manufacturing solid electrolyte, involves throwing the raw material containing lithium sulfide and other sulfide into the reaction tank. The mixture of the raw material is circulated through main circulation path and sub circulation path. The cycle time of the circulation process in the sub circulation path is lesser than 3 hours. The flow rate of the circulation process in the sub circulation path is set in the range of 2L/min-600L/min. The molar ratio of the lithium sulfide and other sulfide is set in the range of 50:50-95:5. The aromatic hydrocarbon-based solvent is contained in the raw material. The toluene is contained in the solvent.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the solid electrolyte manufacturing apparatus. (Drawing includes non-English language text)    Solid electrolyte manufacturing apparatus (1)    Reaction tank (20)    Connection pipes (30,40)    Pumps (46,104)    Connection device (100)    Main circulation path (A)    Sub circulation path (B)