Applicants have found that by adding glass fiber, glass powder, carbon fiber and/or carbon powder as a filler, and a phosphate to a fluororesin such as polytetrafluoroethylene, mixing them homogeneously to obtain a fluororesin composition, pressing and molding it at a normal temperature at 300 to 600 kg/cm2, and baking (heating) it under normal pressure at 360??? to 380??? C., the thus obtained sl