Acrylonitrile-butadiene rubbers (NBR) and hydrogenated crylonitrile-butadiene rubbers (HNBR) have been widely used as oil-resistant elastomers especially in automotive applications. The history of NBR is very old and has ripened as technology. However, the needs to NBR still continue, such as enhance durability, reduce environmental damage, and our contribution to the information technology. These resulted the improvement of NBR to be still is imperative. For this purpose, new NBR have recently been developed. For example, NBR for electronic products was developed by reducing metal ions. The fast-cure-type NBR was developed to increase the rubber part productivity. New technologies such as copolymerization with third monomers, a blend with other polymers and technologies to control polymer structure are applied to NBR. HNBR is excellent in heat and ozone resistances when comparing with NBR. The improvement of both heat and low-temperature resistance is always required. For applying to this demand, new low-temperature flexibility HNBR with highly hydrogenation were developed by precise control of molecular structure and hydrogenation technology. These new HNBRs are suitable applications required wide range of operational temperatures.