In previous study, master S-N curve considering influence of loading condition and pre-strain was determined about simple bending and tension fatigue tests, using equivalent structural stress method and normalized stress. Unlike simple bending and tension specimen, bending process specimen exists residual stress of thickness direction. Therefore, it is necessary to apply stress calculation method reflecting residual stress effect. In this study, master S-N curve of bending process specimen was determined using mean stress effect function which consider influence of residual stress.