Disclosed is a method for producing a sulfide-based solid electrolyte containing an alkali metal, a sulfur element, a phosphorus element and a halogen element, including performing a reaction of an alkali metal sulfide and a substance containing at least one element of a sulfur element, a phosphorus element and a halogen element in an organic solvent having an electron-withdrawing group. The method provides a sulfide-based solid electrolyte having a high ion conductivity.