A method for producing a polymer for oil-resistant rubber, which comprises adding, to an aqueous dispersion of an unsaturated nitrile-conjugated diene copolymer (component A), a monomer composition (component B) containing at least one kind of monomer selected from the group consisting of a nitrile group-containing monomer (component B-1), a (meth)acrylic acid ester monomer (component B-2) and an aromatic vinyl compound monomer (component B-3), and conducting a polymerization reaction in a state that the ratio of the conjugated diene monomer present in the system, to the total monomers present in the system is controlled at 10 mol % or less.