Provided is a method for producing a solid electrolyte having peaks at 2θ=20.2°±0.5° and 23.6°±0.5° in X-ray diffractometry using a CuKα ray and containing a lithium element, a phosphorus element, a sulfur element, and a halogen element, the method including using raw materials containing yellow phosphorus and a compound containing a lithium element, a sulfur element, and a halogen element.