PROBLEM TO BE SOLVED: To provide a sulfide solid electrolyte material having improved Li ion conductivity.SOLUTION: A method for producing an LiI-LiX-LiS-PSsulfide solid electrolyte (where X is Cl, F, or Br) includes: amorphizing a raw material composition containing LiI, LiX (where X is Cl, F, or Br), LiS, and PSto obtain a sulfide glass; heat-treating the sulfide glass at a nucleation temperature of the sulfide glass; and heat-treating the heat-treated sulfide glass at a crystal growth temperature of the sulfide glass.