The applications of polymers and rubber materials to electrical power apparatus and cables are reviewed. Polymers and rubber materials have been widely used as insulation and structure materials because of their excellent electrical/mechanical properties and easy manufacturing. They have played an important role to the development of high-performance apparatus in this half century. OF (Oil-Filled) cables are replaced with cross-linked polyethylene cables except UHV (Ultra High Voltage) AC and DC cables. Polymer insulators become popular in the field of outdoor insulators. Polymeric materials are also very important in transformers, rotating machines, GIS (Gas Insulated Switchgear) and so on.On the other hand, polymers and rubber materials are rather weak at heat-resistance and ageing (degradation). Recent compact and high-performance power apparatus have strongly required the improved heat-resistance and long-term stability of polymers and rubber materials.