DESULFURIZATION SYSTEM FOR FUEL CELL, HYDROGEN PRODUCTION SYSTEM FOR FUEL CELL, FUEL CELL SYSTEM, DESULFURIZATION METHOD FOR HYDROCARBON FUEL, AND METHOD FOR PRODUCING HYDROGEN

A desulfurization system for a fuel cell of the invention includes a fuel supply unit that supplies a hydrocarbon fuel, which contains sulfur compounds, contains oxygen at a volume concentration of 1 ppm to 4%, and has a Wobbe index of 12 kWh/mto 16 kWh/m, at a latter stage portion; and a desulfurization unit that includes a desulfurization catalyst that desulfurizes the hydrocarbon fuel, and the desulfurization catalyst includes an Ag-loaded zeolite and/or a Cu-loaded zeolite.