Welding technology has been developed to improve welding quality. Especially, plasma arc welding has been used for a wide range of areas. However, welding defects occur because of inappropriate arc conditions and lack of arc control with metal vapor contamination in the arc column and anode root. The metal vapor contamination from the anode is varied by the electrical conductivity of the arc in high-temperature medium. The arc emits intense radiation. In this paper, the temperature distribution of the plasma arc contaminated with iron vapor from the anode under consideration of self-absorption was elucidated to develop the plasma arc welding technology and avoid the welding defect. Electromagnetohydrodynamic (MHD) simulation is used to calculate the temperature. Results show that the temperature distribution was varied under consideration of self-absorption because of the iron vapor distribution, and because ionized argon exists near the cathode.