A sulfide solid electrolyte includes a sulfide-based glass phase. The sulfide-based glass phase has an exothermic peak at which a highly ion-conductive crystal is precipitated when subjected to a differential scanning calorimetry measurement at a heating rate of 5° C./min, the exothermic peak can be separated into two or more peaks, and a temperature difference between a peak top of a peak on the highest temperature side and a peak top of a peak on the lowest temperature side among the two or more peaks obtained by the peak separation is 0.5° C. or higher.