NOVELTY - Carbon fiber synthesizing catalysts comprise irreducible inorganic material in a mean particle size of below 500 nm and reducible inorganic material in a mean particle size of below 500, which are pulverized and mixed. The mixture is heat-treated under reduction atmosphere to give metal particles in a mean particle size below 1 microns. The mixed powder of the irreducible inorganic material particles is included in the carbon fibers.    USE - The catalysts are used in producing carbon fibers and for the production of fuel cell catalytic material (claimed). The fuel cell is used as an electric power generating technology.    ADVANTAGE - The catalysts are capable of producing a fuel cell having sufficient output. They provide a fuel cell of high catalytic performance and high output.    DETAILED DESCRIPTION - Carbon (11) fiber synthesizing catalysts (12) comprise irreducible inorganic material in a mean particle size of primary particles below 500 nm and reducible inorganic material in a mean particle size of primary particles below 500, which are pulverized and mixed. The mixture is heat-treated under the reduction atmosphere to give metal particles in a mean particle size below 1 microns. The mixed powder of the irreducible inorganic material particles is included in the carbon fibers.    INDEPENDENT CLAIMS are also included for the following:    (1) fuel cell catalyst material production, comprising synthesizing carbon fibers by thermally decomposing a hydrocarbon under the presence of carbon fiber synthesizing catalysts, and obtaining carbon fibers carrying catalytic particles on the surface and in the inside by carrying catalyst particles on the carbon fibers according to the colloidal method;    (2) a catalyst material comprising catalyst particles carried on carbon fibers and containing a first metal element comprising platinum or ruthenium and a second metal element (other than the first metal element) of below 30 wt.%;    (3) composite carbon materials comprising at least two types of carbon fibers synthesized at different temperatures under the presence of the carbon fiber synthesizing catalyst;    (4) carbon fiber production comprising pulverizing and mixing irreducible inorganic material particles in mean primary particle size below 500 nm and reducible inorganic material particles in mean primary particle size below 500 nm, obtaining a mixed powder of metal particles in a mean particle size below 1 sand the irreducible inorganic material particles as carbon fiber synthesizing catalyst by reducing the obtained mixture by heat treating in a furnace in the reduction atmosphere, and synthesizing carbon fibers by thermally decomposing the hydrocarbon under the presence of the carbon fiber synthesizing catalysts;    (5) electrodes for fuel cell comprising carbon nano-fibers in mean diameter of 100-1000 nm, aspect ratio of more than 10, irreducible oxide powder in diameter of below 100 nm and catalysts for fuel cell carried on the surface of the carbon nano-fibers;    (6) fuel cell electrode production comprising reducing a mixture of transition metal oxide powder and irreducible oxide powder and forming a mixture of transition metal particles and irreducible oxide powder, synthesizing carbon nano-fibers by heating the produced mixture of the transition metal particles and the irreducible oxide powder and bringing gas comprising mainly hydrocarbon gas into contact with the mixture of the heated transition metal particles and the irreducible oxide powder, carrying catalysts for fuel cell on the surfaces of the generated carbon nano-fiber, and forming a membrane by impregnating ion conductive material in the layer comprising the mixture of the carbon nano-fiber carrying the fuel cell catalyst on the surface;    (7) a fuel cell comprising a proton electrolyte layer, a film shape electrode formed on both surfaces of the proton electrolyte layer containing the carbon nano-fiber, irreducible oxide powder and fuel cell catalyst carried on the surfaces of the carbon nano-fibers and ion conductive material, and a collector formed on both surfaces of the respective electrodes;    (8) carbon nano-fiber synthesis comprising bringing a hydrocarbon gas in contact with a mixture of transition metal oxide powder and irreducible oxide powder;    (9) fuel cell electrode layer production comprising impregnating proton conductive material under the reduced pressure to an electrode layer including a skeleton formed with carbon nanofibers and catalyst particles carrying on the carbon nanofibers without impregnated with proton conductive material, and in which a rate of carbon nano-fibers with the catalyst particles carried on the surface and the inside of the carbon nano-fibers is more than 10%; and    (10) a fuel cell catalyst sheet comprising carbon nanofibers, catalyst particles carried on the surfaces of the carbon nano-fibers, and proton conductive material adhered on the surface of the carbon nano-fibers to contact the catalyst particles.    The specific surface area of the carbon nano-fibers according to the Brunauer-Emmett-Teller (BET) method is more than 200 m2/g, a mean fiber size (mu) is above 100 to below 500 nm, and a variance (sigma) in the distribution of the mean fiber size (mu) is less than (1/1.28)(mu-80), where mu is 100-335 or less than less than (1/1.28)(850-mu), where mu is 335-500.    DESCRIPTION OF DRAWING(S) - The figure is a schematic diagram showing the vertical sectional view of a fuel cell catalytic material.    Carbon (11)    Catalyst (12)    Nation (13)