In order to investigate the effect of stress concentration on high cycle fatigue property of austenitic stainless steel, rotating bending fatigue tests were carried out with SUS316L having loose circular notch such as curvature radius of 10-40mm and smooth specimen in the air at room temperature and the water cooling. As the results, it was clear that the ratio of stress concentration factor K_t to fatigue strength reduction factor K_f was about 0.907〜1.015(Water-cooling). And also, the method which obtain the fatigue limit of smooth specimen without the water cooling of the test specimen during fatigue test was proposed.