NOVELTY - Liquefied petroleum gas (LPG) fuel has 2C hydrocarbon compound content of less than or equal to 3 vol%, 4C hydrocarbon compound content of less than or equal to 3 vol%, total sulfur (S) concentration of less than or equal to 10 mass ppm, carbonyl sulfide S content of less than or equal to 2 mass ppm, methyl mercaptan S content of less than or equal to 3 mass ppm, S content of compound having boiling point greater than or equal to that of dimethyl disulfide of less than or equal to 2 mass ppm, methanol concentration of less than or equal to 50 mass ppm, water concentration of less than or equal to 50 mass ppm and remaining 3C hydrocarbon.    USE - For fuel cell system (claimed) which uses hydrogen-containing gas obtained by modification of desulfurized LPG fuel by partial oxidation, self-thermal reformation, steam reformation or carbon dioxide modification process.    ADVANTAGE - The LPG fuel enables stable driving of reformer and stable electric power generation. Desulfurization of LPG fuel is carried out using minimum amount of desulfurization agent. Damage to modification catalyst in the modifier for hydrogen production is prevented.    DETAILED DESCRIPTION - Liquefied petroleum gas (LPG) fuel has 2C hydrocarbon compound content of 3 vol% or less, 4C hydrocarbon compound content of 3 vol% or less, total sulfur concentration of 10 mass ppm or less, sulfur concentration of carbonyl sulfide of 2 mass ppm or less, sulfur concentration of methyl mercaptan of 3 mass ppm or less, sulfur concentration of sulfur compound having boiling point equal to or higher than that of dimethyl disulfide of 2 mass ppm or less, methanol concentration of 50 mass ppm or less, water content concentration of 50 mass ppm or less and remaining 3C hydrocarbon compounds.    INDEPENDENT CLAIMS are included for the following:    (1) desulfurization of LPG fuel which involves naturally vaporizing the fuel and desulfurizing using a desulfurization agent; and    (2) modifying the desulfurized LPG fuel to form hydrogen-containing gas for use in a fuel cell system.    DESCRIPTION OF DRAWING(S) - The figure shows a flowchart of outline of fuel cell system.    Fuel cell system (1)    Water supply pipe (11)    Fuel inlet (12)    Desulfurization agent (23)    Modifier (31)    Fuel cell (34)    Air blower (35)    Waste heat recovery equipment (37)