Since polymeric materials have excellent characteristics, they are used in various applications and can be said to be indispensable materials. However, since the polymer material is inferior in heat resistance, its use range is limited. In a high-temperature environment, polymers decompose due to auto-oxidation process. By improving the heat resistance, it becomes possible to use the polymer for many purposes. Attempts to improving the thermal resistivity of polymers is to add additives typified by antioxidants. By quenching and scavenging the radicals generated by thermal decomposition at high temperature, the antioxidant can greatly improve the heat resistance of the polymer material. However, the antioxidant has a problem that the heat resistance of the antioxidant itself is not so high. This is because the conventional antioxidant is low molecular weight, its function is lowered or decreased by heat denaturation at high temperature. Therefore, in order to further improve the thermal resistance of the polymer material, it is necessary to use an antioxidant having higher heat resistance. Carbon nanotubes (CNT) is a material having a possibility to be used as an antioxidant which can be used under a high temperature environment. CNT has pi-electrons on its surface, has high thermal resistance (~600oC in air) and is a high aspect ratio of fibrous material with a large specific surface area (~1200 m2/g), so it has great potential as a high thermal resistive antioxidant. Super growth single wall carbon nanotube1 (SG-SWNT) is synthesized by CVD, it does not contain a metal catalyst. Furthermore, because of SG-SWNT is a single wall CNT, it is having a very large specific surface area more than 1000 m2/g. Therefore, it is expected to be the CNT having the most excellent antioxidant among CNTs.