TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Properties: The tungsten oxide microparticles have average particle diameter of 15-80 nm and oxygen defect of predetermined ratio. The ratio of oxygen atom number of the crystal microparticles and tungsten atom number is 2.54-2.63. The tungsten oxide microparticles have at least two crystal structures. The catalyst metal has average particle diameter of 2-35 nm.Preferred Composition: Mixture (0.25-5 mol%) of vanadium, chromium, manganese, iron, nickel, copper, niobium, molybdenum, rhenium and titanium is doped with respect to the tungsten oxide microparticles. The ratio of the catalyst metal with respect to the microparticles is 1.8-11 mol%. 28-78% of the total catalyst metal amount is contained in oxidation state. The catalyst metal is platinum, iridium, osmium, palladium, rhodium and/or ruthenium.Preferred Tape: The hydrogen gas detection tape further has protective film laminated on the hydrogen gas detection layer.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Properties: The tungsten oxide microparticles have average particle diameter of 15-80 nm and oxygen defect of predetermined ratio. The ratio of oxygen atom number of the crystal microparticles and tungsten atom number is 2.54-2.63. The tungsten oxide microparticles have at least two crystal structures. The catalyst metal has average particle diameter of 2-35 nm.Preferred Composition: Mixture (0.25-5 mol%) of vanadium, chromium, manganese, iron, nickel, copper, niobium, molybdenum, rhenium and titanium is doped with respect to the tungsten oxide microparticles. The ratio of the catalyst metal with respect to the microparticles is 1.8-11 mol%. 28-78% of the total catalyst metal amount is contained in oxidation state. The catalyst metal is platinum, iridium, osmium, palladium, rhodium and/or ruthenium.Preferred Tape: The hydrogen gas detection tape further has protective film laminated on the hydrogen gas detection layer. EXAMPLE - Tungstic acid (2.5 g) was dissolved in methanol (31 ml) and stirred at room temperature for 30 minutes. Pure water (18 ml) and chloroplatinic acid aqueous solution was added to the tungstic acid solution, to obtain tungstic acid colloidal solution containing catalyst metal. Phthalic acid resin varnish (in wt.%) (15), melamine resin liquid (20), obtained colloidal solution (20), silica (15), xylene/toluene (29) and dispersant (1) were mixed to obtain composition for hydrogen gas detection layer formation. The layer formed using the composition had excellent hydrogen gas leak detection sensitivity.