NOVELTY - Composition comprises a fluororubber (a) and a carbon black (b), where the fluororubber (a) is a vinylidene fluoride-based fluororubber comprising a structural unit derived from vinylidene fluoride (VdF unit) and a structural unit derived from at least one monomer comprising hexafluoropropylene (HFP), 2,3,3,3-tetrafluoro propylene or perfluoro(alkyl vinyl ether) (PAVE), and the fluororubber composition has a difference of delta G1a, (G1a (1%)-G1a (100%)) of 120-3000 kPa.    USE - The fluororubber composition is useful: in a crosslinked fluororubber article, which is useful for a bladder for tire manufacturing (all claimed), where the fluororubber article is useful: for belts for chemical vapor deposition apparatuses, dry etching apparatuses, wet etching apparatuses, oxidation diffusion apparatuses, sputtering apparatuses, ashing apparatuses, washing apparatuses, ion injection apparatuses, exhaust apparatuses, semiconductor manufacturing apparatuses, liquid crystal panel manufacturing apparatuses, plasma panel manufacturing apparatuses, plasma address liquid crystal panels, field emission display panels and solar cell substrates; and in sealing materials such as gaskets and contact or non-contact packing materials, engine bodies, main driving systems, valve systems, lubricating/cooling systems, fuel systems, air intake/ exhaust systems for automotive engines, transmission systems for drive systems, chassis steering systems, braking systems. The sealing material is useful: in driving systems for automotive engines e.g. crankshaft seals or camshaft seals; in valve systems for automotive engines e.g. valve stem oil seals for engine valves and valve seats for butterfly valves; in lubricating/cooling systems for automotive engines e.g. sealing gaskets for engine oil coolers; in aviation, rockets, ships, oil well drilling, chemical plants, pharmaceutical applications, photographic applications such as developers, printing applications such as printing equipment, coating applications such as coating equipment, analytical/scientific instruments, food processing plant equipment, atomic power plant equipment, iron and steel-related applications such as iron plate processing equipment, general industrial applications, electrical applications, fuel cells and electronic components; and as a diaphragm for a fuel system, exhaust system, braking system, drive system or ignition system.    ADVANTAGE - The fluororubber composition exhibits excellent chemical resistance, oil resistance, heat resistance, cold resistance, and tensile strength.    DETAILED DESCRIPTION - Composition comprises a fluororubber (a) and a carbon black (b), where the fluororubber (a) is a vinylidene fluoride-based fluororubber comprising a structural unit derived from vinylidene fluoride (VdF unit) and a structural unit derived from at least one monomer comprising hexafluoropropylene, 2,3,3,3-tetrafluoro propylene or perfluoro(alkyl vinyl ether) (PAVE), the molar ratio of the VdF unit to the structural unit derived from the monomer comprising HFP, 2,3,3,3-tetrafluoropropene or PAVE is 50/50-78/22, where the fluororubber composition has a difference of delta G1a, (G1a (1%)-G1a (100%)) of 120-3000 kPa, the G1a (1%) denotes a modulus of shearing elasticity at a dynamic strain of 1%, G1a (100%) denotes a modulus of shearing elasticity at a dynamic strain of 100%, and G1a (1%) or G1a (100%) are determined by a dynamic viscoelasticity test carried out on an unvulcanized rubber with a rubber process analyzer (RPA) in a condition that the measurement frequency is 1 Hz and the measurement temperature is 100 degrees C.