In order to develop non-heated STAl(super thermal resistant Aluminum alloy) for ampacity gain conductor, the systematic research was carried out. Especailly, the effect of a very small amount of Zr, Sc element in EC grade Al ingot on mechanical and electrical properties was our priority. As a result, it was found that the strength and recrystallization temperature of designed alloy was gradually increased with Zr, Sc addition up to 0.3 wt.%. However, the electric conductivity showed no drastic change. The tensile strength and recrystalliztion temperature, $17.75{sim}20.05;kgf/mm^2$ and $420{sim}520;^{circ}C$, was obtained at 0.3 wt.% Zr, Sc addition, respectively. Particles of the $Al_3Zr$ and $Al_3Sc$ phase affected the ambient and elevated-temperature strength of the alloys.