NOVELTY - A fuel cell system (10) comprises fuel cell, catalyzed combustion apparatus filled with oxidation catalyst which contacts and burns combustible gas to oxidation catalyst, catalytic reaction chamber which is partitioned off with hydrogen permeable membrane and permeated water matter receptacle chamber, hydrogen generating apparatus which is filled with hydrocarbon reforming catalyst into catalytic reaction chamber, steam supply part which supplies steam to catalytic reaction chamber, and hydrogen supply part which supplies hydrogen produced by hydrogen generating apparatus to fuel cell.    USE - Fuel cell system.    ADVANTAGE - The fuel cell system has high energy efficiency.    DETAILED DESCRIPTION - A fuel cell system (10) comprises fuel cell, catalyzed combustion apparatus filled with oxidation catalyst which contacts and burns combustible gas to oxidation catalyst, catalytic reaction chamber which is partitioned off with hydrogen permeable membrane and permeated water matter receptacle chamber, hydrogen generating apparatus which is filled with hydrocarbon reforming catalyst into catalytic reaction chamber, raw material pre-heating apparatus which heats light hydrocarbon using combustion heat produced with catalyzed combustion apparatus, light hydrocarbon supply part which supplies light hydrocarbon heated with raw material pre-heating apparatus to catalytic reaction chamber, oxygen pre-heating apparatus which heats fluid containing oxygen using combustion heat produced with catalyzed combustion apparatus, fluid containing oxygen supply part which supplies fluid containing oxygen heated with oxygen pre-heating apparatus to catalytic reaction chamber, steam pre-heating apparatus which heats steam using combustion heat produced with catalyzed combustion apparatus, steam supply part which supplies steam heated with steam pre-heating apparatus to catalytic reaction chamber, hydrogen supply part which supplies hydrogen produced by hydrogen generating apparatus to fuel cell, and permeated water matter receptacle chamber partitioned off with hydrogen permeable membrane which permeates hydrogen produced from light hydrocarbon in catalytic reaction chamber and isolates from residual gas that remains in catalytic reaction chamber. The hydrogen is produced by decomposing 1 mole methane (CH4) to produce 1 mole carbon (C) and 2 moles hydrogen (H2), decomposing alkyl of formula CnH2n+2 to produce n mole carbon (nC) and n mole of hydrogen ((n+1)H2), synthesizing 1 mole carbon and one half mole oxygen (O2) to produce 1 mole carbon monoxide (CO), displacing 1 mole carbon and 1 mole water (H2O) to produce 1 mole hydrogen and 1 mole carbon monoxide,reacting 1 mole methane and 1 mole water to produce 3 moles hydrogen and 1 mole carbon monoxide or reacting 3 moles hydrogen and 1 mole carbon monoxide to produce 1 mole methane and 1 mole water, or reacting 1 mole carbon monoxide and 1 mole water to produce 1 mole hydrogen and 1 mole carbon dioxide or reacting 1 mole hydrogen and 1 mole carbon dioxide to produce 1 mole carbon monoxide and 1 mole water.    n= greater than or equal to 2.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic diagram of the fuel cell system.    Fuel cell system (10)    Composite pre-heater (20)    Air heating part (22)    Steam heating part (24)    Raw material heating part (26)