NOVELTY - The gas decomposing element (110) has electrode layers (102,105) that are provided in the sides of the solid electrolyte layer (101) respectively. The element main portion is provided, so that the mixture ratio of the catalyst (151,152) provided in the electrode layers is changed toward the flow direction of gas. The mixture ratio is reduced and increased toward flow direction of gas, when catalyst components are provided respectively. The catalyst is mixed in material of electrode layer.    USE - Gas decomposing element for gas decomposition electric power generating apparatus (claimed).    ADVANTAGE - The decomposition efficiency of gas can be improved by adopting the catalyst of the optimal mixture ratio corresponding to the change of the gas concentration of a decomposition process.    DETAILED DESCRIPTION - The mixture ratio of catalyst is changed in catalyst layer while providing catalyst layer in surface of solid electrolyte layer and electrode layer. The mixture ratio of catalyst is changed while adding catalyst to collector provided along the electrode layer. The catalyst component decomposes ammonia to generate hydrogen molecule. Another catalyst component decomposes hydrogen molecule to produce proton. The catalyst component is made of iron, cobalt, titanium, molybdenum, tungsten, manganese, ruthenium and copper. Another catalyst component is made of nickel, cobalt, titanium, molybdenum, tungsten, manganese, ruthenium and copper. INDEPENDENT CLAIMS are included for the following:    (1) gas decomposition electric power generating apparatus; and    (2) gas decomposing element manufacturing method involves providing electrode layers in sides of solid electrolyte layer. The catalyst is provided so that mixture ratio of electrode layers is changed toward the flow direction of gas.    DESCRIPTION OF DRAWING(S) - The drawing shows a sectional view illustrating the change of the mixture ratio of the catalyst of the gas decomposing element.    Solid electrode layer (101)    Electrode layers (102,105)    Gas decomposing element (110)    Catalysts (151,152)