NOVELTY - A fuel generator (1) comprises gas inflow port (14) to which oxidizing gas is supplied from outside, gas outflow port (15) which supplies fuel gas outside, fuel generation component which produces fuel gas by oxidation reaction with oxidizing gas, accommodating part (17) which is provided between gas inflow port and gas outflow port and accommodates fuel generation component, air-intake valve (16) provided between gas inflow port and accommodating part, and exhaust valve (18) provided between accommodating part and gas outflow port.    USE - A fuel generator for fuel cell system (claimed).    ADVANTAGE - The fuel generator and fuel cell system have high durability because the generation amount of the fuel gas from the fuel generator increases, and the battery capacity of the fuel cell system increases.    DETAILED DESCRIPTION - A fuel generator (1) comprises gas inflow port (14) to which oxidizing gas is supplied from outside, gas outflow port (15) which supplies fuel gas outside, fuel generation component which produces fuel gas by oxidation reaction with oxidizing gas, accommodating part (17) which is provided between gas inflow port and gas outflow port and accommodates fuel generation component, air-intake valve (16) provided between gas inflow port and accommodating part, and exhaust valve (18) provided between accommodating part and gas outflow port. The air-intake valve, the accommodating part, and the exhaust valve and its units (11-13) are multiply provided, the units are connected in parallel, and the exhaust valve has 1st opening and 2nd opening which has smaller opening degree than 1st opening. When the exhaust valve is made into a 1st opening degree for every unit by shifting a period, the air-intake valve is made into a 3rd opening degree. When the exhaust valve is made into a 2nd opening degree, the air-intake valve is made into a 4th opening degree larger than a 3rd opening degree. The generated fuel gas is reducible gas by oxidation reaction with an oxidizing gas. An INDEPENDENT CLAIM is included for fuel cell system comprising fuel generator and fuel cell apparatus which produces electric power by using fuel gas supplied from fuel generator.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic diagram of the structure of the fuel generator.    Fuel generator (1)    Units (11-13)    Gas inflow port (14)    Gas outflow port (15)    Air-intake valve (16)    Accommodating part (17)    Exhaust valve (18)