Stainless steel sheets are widely used as the structural material for the railroad cars and the commercial vehicles. These kinds of structures used stainless steel sheets are commonly fabricated by using the gas welding. For fatigue design of gas welded joints such as fillet and plug type joint, it is necessary to obtain design information on stress distribution at the weldment as well as fatigue strength of gas welded joints. And also, the influence of the geometrical parameters of gas welded joints on stress distribution and fatigue strength must be evaluated. Thus, in this paper, ${Delta}P-N_f$ curves were obtained by fatigue tests. Using these results, ${Delta}P-N_f$ curves were rearranged in the. ${Delta}{sigma}-N_f$ relation with the hot spot stresses at the gas welded joints.