In this paper, to clarify the effect of fatigue strength improvement by peening away from weld toe, plate bending fatigue tests under stress ratios R = 0, -1 and -infinity were carried out with out-of-plane gusset specimens. In the fatigue tests, the peening locations of 5 to 25 mm away from weld toe were considered. Furthermore, the effect of improvement of fatigue strength by peening on the back surface of the weld toe was also investigated. The fatigue test results showed the fatigue strength was significantly improved under the stress range of 80N/mm² and stress ratio R = -infinity by peening 20mm away from weld toe or back surface of the weld toe.