NOVELTY - The hydrogen production apparatus has a modifier (3A), a source gas supply path (4), a source gas supply device, a combustor (5), an ignition device (5A), a combustible gas-supply path, a valve (7), and a controller to control source gas supply device and ignition device, and replenishes source gas to gas flow path between source gas supply device and valve, and maintains pressure in gas flow path during stop more than threshold value. The source gas is supplied even in ignition operation of ignition device, when abnormality is detected.    USE - Hydrogen production apparatus is used for fuel cell system (claimed).    ADVANTAGE - The hydrogen production apparatus reduces abnormality in combustion operation of combustor at initial stage.    DETAILED DESCRIPTION - The hydrogen production apparatus has a modifier (3A) to produce hydrogen-containing gas by modification reaction from source gas, a source gas supply path (4) to supply source gas to the modifier, a source gas supply device provided on source gas supply path, to control supply of source gas to modifier, a combustor (5) burn gas comprising modifier, an ignition device (5A) provided in the combustor, a combustible gas-supply path to supply gas from modifier to combustor, a valve (7) provided in the combustible gas-supply path, controller to control source gas supply device and ignition device, and replenishes source gas supply device, replenishes source gas to gas flow path between source gas supply device and valve, and maintains pressure in the gas flow path during stop more than threshold value. The source gas is supplied in ignition operation of ignition device, when abnormality is detected. An INDEPENDENT CLAIM is included for operation of the hydrogen production apparatus.    DESCRIPTION OF DRAWING(S) - The drawing shows the schematic structure of fuel cell system. (Drawing includes non-English language text)    Water supply device (2)    Hydrogen generator (3)    Modifier (3A)    Source gas supply path (4)    Combustor (5)    Ignition device (5A)    Fuel gas supply path (6)    Valve (7)    Fuel cell (50)