In the previous report, the authors described the investigation on a cracking phenomenon and its reproducing test results, as to the toe in a full penetrated T-type fillet joint of thick steel plate. Continued, after that, in wide range of welding conditions, the authors assured the effects of factors on toe crack initiation, and the welding procedures to prevent cracking, and summary results were obtained as follows : - 1. Elimination of notched effect at the toe is one of the most effective ways for the prevention of cracking. For this purpose, in the joint used thicker plate such as 50mm or more, and material of inferior ductility, the procedure like the finish of the toe by grinding is necessary before opposite side welding, while in the case of the welding of some 20mm thick plate the applications of both flat position and finer diameter electrode are adequate. 2. Welding Metal extremely different in mechanical properties with mother metal should be avoidable. 3. To decrease the welding strain at the toe which would cause the crack in the opposite side welding, back-chipping depth less than half plate thickness or edge preparation made with larger depth of first pass side groove is suggested. 4. Welding alternatively from both sides of surfaces is suitable to prevent the crack in ultra thick plates where there may arise a problem with respect to angular distortion or root cracking in multi-pass welds.