NOVELTY - Oxygen-containing gas (O) and source gas (f1) containing water steam and hydrocarbon-type fuel, are mixed in a mixing chamber. The mixed gas (f2) is guided to a catalytic-reaction chamber via a force chamber, at preset temperature. The mixed gas is contacted with a modification catalyst, and hydrogen-containing gas is manufactured by partial oxidation and steam reforming reaction.    USE - For manufacturing hydrogen-containing gas used as fuel for fuel cell.    ADVANTAGE - The hydrogen-containing gas is reliably and stably manufactured with favorable modification efficiency, by preventing problems such as reduction of catalytic activity.    DETAILED DESCRIPTION - Oxygen-containing gas (O) and source gas (f1) containing water steam and hydrocarbon-type fuel, are mixed in a mixing chamber. Mixed gas (f2) is guided to catalytic-reaction chamber via force chamber provided at upstream side of reaction chamber. Mixed gas is contacted with modification catalyst, and hydrogen-containing gas is manufactured by partial oxidation and steam reforming reaction. Minimum temperature at which modification catalyst generates partial oxidation reaction is set as partial-oxidation minimum temperature (T1). Similarly, minimum temperature at which modification catalyst generates steam modification reaction is set as steam-reforming minimum temperature (T2). Temperature at which mixed gas carries out auto-ignition in advection time required for mixed gas to reach catalytic-reaction chamber from mixing chamber, is set as auto-ignition temperature (T3). Mixed gas is fed to reaction chamber by setting temperature of mixing chamber and force chamber to temperature, which is less than temperature (T2) and more than temperature (T1), and at temperature less than the temperature (T3). An INDEPENDENT CLAIM is included for manufacturing apparatus of hydrogen-containing gas.    DESCRIPTION OF DRAWING(S) - The figure shows the relationship between catalytic-reaction room temperature and inlet port temperature in catalytic reaction chamber. (Drawing includes non-English language text)