SULFIDE SOLID ELECTROLYTE

Provided is a sulfide solid electrolyte having: diffraction peak A observed within a range of 2θ = 20.0° to 24.0°; and diffraction peak B observed within a range of 2θ = 24.4° to 26.4°, diffraction peak A and diffraction peak B being observed by performing X-ray diffraction measurement using CuKα1 radiation, and the ratio of IA to IB, IA/IB, being 2.0 or less, wherein IA is an intensity of diffraction peak A and IB is an intensity of diffraction peak B. Preferably, the sulfide solid electrolyte contains elemental lithium, elemental phosphorus, elemental sulfur, and an elemental halogen. It is also preferable that the sulfide solid electrolyte has an argyrodite-type crystal structure. It is also preferable that the sulfide solid electrolyte contains a lithium halide hydrate.