TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Condition: The reaction temperature is 600degreesC or less, preferably 200-500degreesC. The water vapor pressure is maintained below atmospheric pressure, preferably 0.3 times or less of atmospheric pressure.Preferred Method: The heat energy required for reaction of iron carbide and water vapor is supplied by contacting water vapor or another gas more than reaction temperature directly, or by contacting solid, liquid or gas more than reaction temperature indirectly. Iron carbide is oxidized and/or hydrated at 600degreesC or more, to obtain gas containing enameling iron, hydrogen and carbon monoxide. The produced hydrogen is separated with water. The oxidized and/or hydrated iron carbide is restored by natural gas, coal, or fossil fuel and/or biomass, and iron carbide is regenerated. Coal and air or oxygen less than a quantity required for coal combustion are supplied to the oxidized and/or hydrated iron carbide. Partial combustion of coal is performed, to produce carbon monoxide and methane gas, and regenerate iron carbide. The separation of coal ash produced by combustion of coal and regenerated iron carbide is performed by magnetic separation. Coal ash and oxidized and/or hydrated iron carbide are separated by magnetic separation. The heat energy required for reaction of iron carbide and water is supplied by sensible heat of regenerated iron carbide. Portion(s) of enameling iron is carbonized with carbon monoxide and methane gas, to regenerate iron carbide. The regenerated iron carbide is reacted with water vapor.    TECHNOLOGY FOCUS - MECHANICAL ENGINEERING - Preferred Components: The hydrogen manufacturing apparatus further has heating unit for heating oxidized and/or hydrated iron carbide, regeneration reactor and magnetic separator. The heating unit is fluid bed-type heating furnace. The reactor (10) is fixed bed, fluid bed (20), moving bed or carrying layer. A natural gas or coal is supplied to the regeneration reactor, which is a fluid bed.