A nitrile rubber composition comprising 5 to 50 parts by weight of carbon black, 5 to 60 parts by weight of graphite having an average particle diameter of 5 μm or less, 5 to 50 parts by weight of conductive carbon other than carbon black and graphite, and, as antioxidants, 1 to 5 parts by weight of alkylated diphenylamine comprising a diphenylamine reaction product with styrene and 2,4,4-trimethylpentene, and 0.5 to 2.5 parts by weight of N,N′-di-2-naphthyl-p-phenylenediamine or dilauryl thiodipropionate, based on 100 parts by weight of nitrile rubber. The nitrile rubber composition can yield a vulcanization molded product, besides maintaining characteristics as a conductive material, satisfying muddy water resistance, sealing properties, and low torque characteristics required for rolling bearing oil seals for vehicles, etc., and having a rubber volume change coefficient kept low when the product is washed with water after exposure to an antifreezing agent.