NOVELTY - Reformer (5) has a catalyst for converting hydrocarbons having 2 or more number of carbon atoms, which are present in source gas, into methane, in presence of hydrogen. Internal reforming-type fuel cell (7) has a fuel electrode (35) to which heating gas containing methane, is supplied from the reformer. Heating gas is reformed to gas containing hydrogen, in presence of water, in fuel cell.    USE - For generating electric power, using internal reforming type fuel cell.    ADVANTAGE - Since hydrocarbons having 2 or more number of carbon atoms are removed from the heating gas supplied to the fuel electrode, there is a few possibility that carbon may precipitate on the fuel electrode, even if the supply amount of water to the fuel electrode, is less. Since sulfide present in the source gas is adsorbed by the catalyst, poisoning of the fuel electrode by sulfide, is prevented. Enables efficiently converting hydrocarbons having 2 or more number of carbon atoms, into methane, by heating the source gas using the heat of the waste gas ejected from the fuel electrode. Improves the power generation efficiency of the system. Prevents conversion of the hydrocarbons, into hydrogen and carbon monoxide, in the reformer, by suitably setting the temperature of the reformer. Prevents precipitation of carbon in the reformer, by using rhodium or ruthenium as the catalyst. Enables maintaining the reformer at the suitable temperature, by utilizing the heat produced in the fuel cell.    DETAILED DESCRIPTION - An electrolyte is interposed between the fuel electrode, and an electrode (31) to which oxygen-containing gas is supplied. The catalyst has desulfurizing effect. A mixing unit mixes waste gas ejected from the fuel electrode, with source gas, and heats the source gas, before source gas is supplied to the reformer. The temperature of the catalyst is maintained at 400 degrees C or more and 500 degrees C or less, by a heat-retention unit which heats the reformer using the heat of the fuel cell.    DESCRIPTION OF DRAWING(S) - The figure shows an outline block diagram of a power generation system. (Drawing includes non-English language text).    power generation system (1)    reformer (5)    fuel cell (7)    electrode (31)    fuel electrode (35)