NOVELTY - A pressure control mechanism is provided in raw material supply mechanism, transport gas supply structure or in heating gas supply structure to control total pressure of gas supplied, depending on load of fuel cell.    USE - For forming hydrogen rich heating gas for feeding to fuel cells.    ADVANTAGE - Increases reliability and efficiency. Alarms on leakage of dangerous gases, and promotes preventing leakages.    DETAILED DESCRIPTION - A raw material supply mechanism feeds raw material to a chemical reaction portion that forms a vapor containing hydrogen gas. A separation layer permeates only hydrogen from the mixed gas to be extracted using a transport gas supplied by a transport gas supply structure. The transport gas supply structure circulates the gas through the fuel cell. A heating gas supply structure feeds extracted hydrogen to a fuel cell. A pressure control mechanism such as a pump or a diaphragm is arranged in the heating gas supply structure to increase the pressure of hot gas, during high load running. Alternately, the pressure control mechanism is arranged in either raw material supply mechanism or transport gas supply structure, so as to control the total pressure of raw material or transport gas for enlarging partial pressure of hydrogen in chemical reaction portion during high load. Alternately the raw material supply mechanism and the transport gas supply structure are individually provided with pressure control mechanisms for increasing total pressures of raw material gas and transport gas during highload maintaining the total pressure difference raw material of transport gas as a fixed value, and to control pressure in extraction portion to be greater than pressure in chemical reaction portion. A leakage detector such as a carbon monoxide sensor checks the leakage of gases other than hydrogen such as carbon monoxide in the downstream side of filter based on a parameter valve and provides a warning accordingly. An INDEPENDENT CLAIM is included for a method of forming hydrogen rich heating gas that involves controlling pressure of raw material and transport gas based on input load. The pressure in extraction portion is reduced below pressure in reaction portion, when a leakage is detected.    DESCRIPTION OF DRAWING(S) - The figure is a flowchart explaining pressure control process.