NOVELTY - A sulfide solid electrolyte material comprises lithium, potassium, silicon, phosphorus and sulfur, and has peak in the position of 2( theta ) of 29.58 plus minus 0.5 degrees in X-ray-diffraction measurement using copper-K( alpha )-ray. The sulfide solid electrolyte material has peak or does not have peak in the position of 2( theta ) of 27.33 plus minus 0.5 degrees in X-ray-diffraction measurement using copper-K( alpha )-ray. The molar ratio of phosphorus with respect to the total amount of silicon and phosphorus is 0.5-0.7. The molar fraction potassium with respect to the total amount of lithium and potassium is 0-0.1 (excluding 0).    USE - Sulfide solid electrolyte material is used in battery (claimed) e.g. lithium cell. Uses include but are not limited to personal computer, video camera, mobile telephone, communication apparatus, motor vehicle, electric vehicle and hybrid vehicle.    ADVANTAGE - The sulfide solid electrolyte material has excellent ionic conductivity.    DETAILED DESCRIPTION - A sulfide solid electrolyte material comprises lithium, potassium, silicon, phosphorus and sulfur, and has peak in the position of 2( theta ) of 29.58 plus minus 0.5 degrees in X-ray-diffraction measurement using copper-K( alpha )-ray. The sulfide solid electrolyte material has peak or does not have peak in the position of 2( theta ) of 27.33 plus minus 0.5 degrees in X-ray-diffraction measurement using copper-K( alpha )-ray. The ratio of diffraction intensity (Ia) of a peak of 2( theta ) of 29.58 plus minus 0.5 degrees and diffraction intensity (Ib) of a peak of 2( theta ) of 27.33 plus minus 0.5 degrees is less than 1. The molar ratio of phosphorus with respect to the total amount of silicon and phosphorus is 0.5-0.7. The molar fraction potassium with respect to the total amount of lithium and potassium is 0-0.1 (excluding 0). INDEPENDENT CLAIMS are included for the following:    (1) battery (10); and    (2) manufacture of sulfide solid electrolyte material.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of battery.    Positive electrode active material layer (1)    Negative electrode active material layer (2)    Electrolyte layer (3)    Positive electrode electrical power collector (4)    Battery (10)