For large-scale illumination necessary for emergency, a brightness and light color becomes the problem. The radiation emitted from the arc becomes very high intensity. Some researchers have researched the HID (High-Intensity Discharge) lamp which is one of the arc lamp with mixed metal vapor, and the line spectrum emitted from the metal vapor is used for improvement of color rendering spectrum. The broad spectrum emitted from continuous spectrum is needed for improvement of color rendering spectrum. Previous research has elucidated the spectrum control for the color rendering improvement of the argon arc mixed with scandium vapor. In addition, it is necessary to perform the calculation using the wall-stabilized arc at a uniform the contribution to the temperature distribution which the convection gives it to bell-shaped form in the gas flow-stabilized arc for the axial distance. Therefore, the model of the cope of radiation power and color rendering should be suggested. This research elucidates the contribution to improvement of color rendering on wall-stabilized argon arc affected by current and wall radius. The radiation power and color rendering increases because of temperature increment derived from the current increment (Joule's heating). Thus, improvement of radiation power and color rendering with controlled by the current and wall radius because of the temperature distribution for significant temperature effect on wall-stabilized argon arc.