SULFIDE SOLID ELECTROLYTE, ALL SOLID STATE BATTERY, AND METHOD FOR PRODUCING SULFIDE SOLID ELECTROLYTE

A main object of the present disclosure is to provide a sulfide solid electrolyte with excellent water resistance. The present disclosure achieves the object by providing a sulfide solid electrolyte including a LGPS type crystal phase, and containing Li, Ge, P, and S, wherein: when an X-ray photoelectron spectroscopy measurement is conducted to a surface of the sulfide solid electrolyte, a proportion of Ge with respect to total amount of Ge is 20% or more.