NOVELTY - A hydrogen producing apparatus comprises modification catalyst layer (1) which generates reformed gas which performs steam reforming reaction with water vapor from water supply apparatus (5) and source gas supplied from material supply apparatus (4), carbon monoxide removal catalyst layer (2) which reduces carbon monoxide in reformed gas, carbon monoxide removal heater which heats carbon monoxide removal catalyst layer, and carbon monoxide removal temperature detection part which detects temperature of carbon monoxide removal catalyst layer and burner (3) which has air supply apparatus.    USE - Hydrogen producing apparatus for home-use fuel cell power generating device.    ADVANTAGE - The apparatus is safe and stable and prevents production of soot.    DETAILED DESCRIPTION - A hydrogen producing apparatus comprises modification catalyst layer (1) which generates reformed gas which performs steam reforming reaction with water vapor which evaporates water from water supply apparatus (5) and source gas supplied from material supply apparatus (4), carbon monoxide removal catalyst layer (2) which reduces carbon monoxide in reformed gas, carbon monoxide removal heater which heats carbon monoxide removal catalyst layer, carbon monoxide removal temperature detection part which detects temperature of carbon monoxide removal catalyst layer and burner (3) which has air supply apparatus, generated gas flow path which supplies generated gas from carbon monoxide removal catalyst layer to burner, exit shut off valve which opens and closes flow path in middle of generated gas flow path, water inlet shut off path of water of exit side of water supply apparatus, material inlets shut off valve which opens and closes flow path of raw material of exit side of material supply apparatus, and control unit which controls supply of source gas in burner. An INDEPENDENT CLAIM is included for a start-stop process of the hydrogen producing apparatus.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic block diagram of the hydrogen-producing apparatus. (Drawing includes non-English language text).    Modification catalyst layer (1)    Carbon monoxide removal catalyst layer (2)    Burner (3)    Material supply apparatus (4)    Water supply apparatus (5)