Provided are: a nitrile rubber composition which contains a carboxyl group-containing nitrile rubber and a reactive silicone oil; and a crosslinked rubber product which is obtained using the nitrile rubber composition. Also provided is a rubber composition for sliding members, which contains: a carboxyl group-containing rubber that contains 0.1-20% by weight of a carboxyl group-containing monomer unit, 20% by weight or less of a monomer unit having an unsaturated carbon-carbon double bond, and 5% by weight or less of a monomer unit having a halogen atom; and a reactive silicone oil.
