To provide a polymer alloy formed of a non-polar rubber and a polar rubber, and a rubber product, which are improved in ozone resistance (weather resistance) while having oil resistance and can achieve high mechanical strength (in particular, tensile strength), and a production method thereof.A rubber product in which an organic peroxide or other cross-linking agent is used to cross-link a polymer alloy comprising: a modified rubber in which EPDM, NR, or another non-polar rubber having a non-conjugated double bond is modified with 2-methoxy-1-naphthonitrile oxide, 2,6-dimethoxybenzonitrile oxide, or another nitrile oxide of an aromatic nitrile oxide derivative; and nitrile rubber, acrylic rubber, or another polar rubber.