NOVELTY - A controller stops the supply of liquid from outside, when quantity of liquid fuel stored in a primary liquid fuel tank (6) reaches predefined value. A desulfurizer (4) filled with desulfurizing agent reduces content of sulfur compound in liquid fuel. A gas/liquid separation apparatus (11) separates the gas from liquid fuel. A liquid fuel recycle piping (45) is extended from the liquid phase of a bypass fuel gas liquid separator (82) of separation apparatus and positioned on fuel tank, when setting liquid fuel density to satisfy predetermined conditions.    USE - Liquid fuel desulfurization apparatus for fuel cell electric power generation system (claimed).    ADVANTAGE - Mixing of combustible gas and air within the container can be suppressed, while supplying liquid fuel to the reformer stably, by using a simple structure. Hence, fuel cell electric power generation system can be driven safely.    DETAILED DESCRIPTION - The liquid level control unit has a float that floats on the liquid phase of the bypass fuel gas liquid separation unit. A self-powered type liquid level controlling valve which is provided in the exit from bypass fuel gas liquid separation unit, is opened and closed by the float. The amount of liquid fuel stored by bypass fuel gas liquid separation unit is controlled to satisfy predetermined conditions relating the perpendicular height of bypass fuel gas liquid separation unit to liquid level upper limit, liquid phase cross sectional area of bypass fuel gas liquid separation unit. The valves are provided in the middle of extraction piping and bypass piping, and are opened when height of liquid level of the bypass fuel gas liquid separation unit more than predetermined height. An INDEPENDENT CLAIM is included for fuel cell electric power generation system which has a reformer that generates reformed gas while supplying liquid fuel stored in the secondary liquid fuel tank. A fuel cell main portion supplies reformed gas generated from the reformer when setting density of liquid fuel in primary fuel tank to satisfy predetermined conditions relating the filling rate of desulfurizing agent in desulfurizer, desulfurizer operating temperature, volume of primary liquid fuel tank and volume of desulfurizer. The reformer is equipped with a burner combustion portion that heats the reformation vessel stored with the reformed gas. An extraction piping is connected to the burner combustion portion of modifier.    DESCRIPTION OF DRAWING(S) - The drawing shows a block diagram of the liquid fuel desulfurization apparatus. (Drawing includes non-English language text)    Desulfurizer (4)    Primary liquid fuel tank (6)    Gas/liquid separation apparatus (11)    Liquid fuel recycle piping (45)    Bypass fuel gas liquid separator (82)