NOVELTY - A reformer (30) for a fuel cell system (100) comprises a case; heat source (35) disposed in case, where heat source contains a mesh, an oxidation catalyst layer disposed on surface of the mesh, and fuel injection nozzle for supplying fuel to the catalyst layer to generate heat energy by oxidation reaction between fuel and oxidant; and a reforming reaction part (39) disposed in the case to generate hydrogen gas from fuel using heat energy generated by heat source.    USE - As reformer for a fuel cell system used for generating hydrogen (claimed) and for generating electricity; and also for polymer electrolyte membrane fuel cells used as portable power source for vehicles, distributed power source for houses and public buildings and a miniature power source for electronic devices.    ADVANTAGE - The reformer for a fuel cell system prevents backfire and improves efficiency of heat transfer. The reformer has improved structure for supplying fuel and an oxidation gas. The fuel cell containing the reformer exhibits superior output characteristics, lower operating temperatures and fast starting and response characteristics compared to other types of fuel cells. The reformer is capable of supplying fuel to oxidation catalyst uniformly and preventing backfire.    DETAILED DESCRIPTION - A reformer (30) for a fuel cell system (100) comprises a case; a heat source (35) disposed in the case, where the heat source contains a mesh, an oxidation catalyst layer disposed on a surface of the mesh, and at least one fuel injection nozzle configured for supplying a fuel to the oxidation catalyst layer to generate heat energy by an oxidation reaction between the fuel and an oxidant; and a reforming reaction part (39) disposed in the case, configured to generate hydrogen gas from the fuel using heat energy generated by the heat source. The at least one fuel injection nozzle comprises a tube containing nozzle holes disposed on an external surface of the tube; and an open first end, and a filler disposed at the first end. The filler comprises at least one of aluminum beads, quartz beads and a mesh. An INDEPENDENT CLAIM is included for a fuel cell system comprising: a reformer configured for generating hydrogen gas from a fuel containing hydrogen by a catalytic chemical reaction using heat energy; and at least one electricity generating unit (11) configured for generating electrical energy by an electrochemical reaction between the hydrogen gas and oxygen, where the reformer contains case, heat source disposed in the case, where the heat source contains a mesh, an oxidation catalyst layer formed on a surface of the mesh, and at least one fuel injection nozzle configured for supplying the fuel to the oxidation catalyst layer to generate heat energy by an oxidation reaction between the fuel and an oxidant, and a reforming reaction part disposed in the case, configured to generate hydrogen gas from the fuel using the heat energy generated by the heat source.    DESCRIPTION OF DRAWING(S) - The figure shows schematic block diagram of a fuel cell system.    Stack (10)    Electricity generating unit (11)    Reformer (30)    Heat source (35)    Reforming reaction part (39)    Fuel supply (50)    Fuel tank (51)    Fuel pump (53)    Air supply (70)    Air pump (71)    Fuel cell system (100)