Abstract: There is provided a technique for manufacturing a hydrogen-containing gas. An oxygen-containing gas is mixed with a feed gas obtained by mixing steam with a hydrocarbon fuel, this mixture is introduced into a catalytic reaction chamber, and a partial oxidation reaction and a steam reforming reaction are conducted to obtain a hydrogen-containing gas. In this reforming, an antechamber of the catalytic reaction chamber is heated up to a self-ignition temperature in a first catalyst section, where the self-ignition temperature is the temperature at which a mixed gas self-ignites during the advection period required for the mixed gas to move from a mixing chamber to the catalytic reaction chamber, with this temperature being at least a minimum partial-oxidation temperature and lower than a minimum steam reforming temperature.