The individual's perception of stress is essential in its experience and on the other hand, the same stressful events create different effects in people, so the question is whether capable nurses have more or less stress? This study was conducted to determine the relationship between self-effi cacy and job stress among nurses. Participants in this study were nursing staffs of affi liated hospitals of Semnan University of Medical Sciences in Iran in 2015-2016. The results showed that 62.7% of the nursing staffs who had not self-effi cacy, had mild job stress and between the levels of job stress and self-effi cacy of the participants was signifi cant (P<0.001). There were signifi cant negative relationships among role overload (B=-0.26, P=0.003), role insuffi ciency (B=-0 .58, P<0.001), role ambiguity (B=-0.455, P<0.001), role boundary (B=-0.706, P<0.001) and responsibility (B=-0.207, P=0.022) with the participants' self-effi cacy. The results of this study showed that job stress among nurses infl uences on the personal, emotional and cognitive effectiveness in nurses and can bring some organizational outcomes such as reduced properly function in the workplace.