NOVELTY - A hydrogen generator manufactures hydrogen-containing reformed gas using hydrocarbon, alcohol or ether fuel, oxygen or air, and water or water vapor. A space longer than the width of the opening of a honeycomb-type catalyst, is provided at the direction through which the raw material flows into combustion-catalyst layer (54) and modification-catalyst layer (55) using a cylindrical honeycomb-type catalyst having an opening. A space is also provided between the combustion-catalyst layer and the modification-catalyst layer.    USE - For fuel cell systems (claimed), such as polymer electrolyte fuel cell system, useful as domestic cogeneration system.    ADVANTAGE - The hydrogen generator enables stable running of polymer electrolyte fuel cell systems over a long period of time. A stable hydrogen-production capability is maintained even when the catalyst of the combustion-catalyst layer deteriorates. Since the catalyst surface area of the disorder effect of gas flow is increased, the temperature peak of gas flow direction is reduced and temperature within combustion-catalyst layer is homogenized. The calorific value by combustion of the raw material in the combustion-catalyst layer is lowered by controlling the active ingredient amount of the divided honeycomb catalyst in the combustion-catalyst layer.    DETAILED DESCRIPTION - A hydrogen generator manufactures hydrogen-containing reformed gas by modification reaction in a fuel-modification portion equipped with a combustion-catalyst layer (54) and a modification-catalyst layer (55), by using hydrocarbon, alcohol or ether fuel, oxygen or air, and water or water vapor as raw material. A space longer than the width of the opening of a honeycomb-type catalyst, is provided at the direction through which the raw material flows into the combustion-catalyst layer and the modification-catalyst layer using a cylindrical honeycomb-type catalyst having an opening. The combustion-catalyst layer is divided, and a space is also provided between the combustion-catalyst layer and the modification-catalyst layer. An INDEPENDENT CLAIM is included for fuel cell system.    DESCRIPTION OF DRAWING(S) - The figure shows the explanatory drawing of the structure and temperature distribution of modification portion. (Drawing includes non-English language text)    Combustion-catalyst layer (54)    Modification-catalyst layer (55)    Electric furnace (110)