Rubber cross-linked product

alpha, beta-ethylenically unsaturated nitrile monomer units and alpha, have beta-ethylenically unsaturated dicarboxylic acid monoester monomer unit, a highly saturated nitrile rubber iodine value is 120 or less (a), polyamine crosslinking agent (b), obtained by crosslinking the highly saturated nitrile rubber composition containing a filler (c), a cross-linked rubber for fluorohydrocarbon gas seal, said highly saturated nitrile rubber composition in the middle, with respect to the highly saturated nitrile rubber (a) 100 parts by weight of the content of the polyamine crosslinking agent (b) is from 0.5 to 20 parts by weight, the content of the filler (c) 10 to 300 parts by weight, to provide a fluoro hydrocarbon gas sealing rubber cross-linked product storage elastic modulus E 'is 5MPa or more at 0.99 ° C..