The purpose of this process is to get the arc welded joint of thick plate economically. In this process the coating material of an electrode is partially removed (Fig. 3) so that the arc strike not only downward frori electrode tip but also extend to a side. The but t joitr of thick plate are prepared with deposits metals as illustrated in Fig. 4, instead of U or double-U scarfing. The grooved area i, e, gap of two plates is so narrow that an electrode can scarcely be permitted to enter the space. Use this electrode when a sufficient penetration of deposite metal into the side wall (or beveled surface) is not obtained. Mechanical strength and shrinkage of this joint are not inferrior to the joint of the usual method. This process is suitable to the welding of thick plate especially the weld length is comparatively short. Frame work of a locomotive boiler bed could be welded economically by this process.