The purpose of this study is to verify the correlation between leader s machiavellianism and organization cynicism. To this end, the overall mechanism of the research model was investigated through the mediating effect of hindsight bias and the moderating effect of ethical leadership. To verify the hypothesis, the survey was conducted twice with 335 employees working in various industries at intervals of 7 days, and the common method bias was minimized by presenting the conciseness of the questionnaire. Control variables were used to confirm a clear causal relationship between independent and dependent variables by using position and negative/positive. As a result of the study, first, it was found that leader s machiavellianism had no statistical significance with organizational cynicism. Second, it was found that relationship between leader machiavellianism and organizational cynicism was mediated by hindsight bias. Third, it was found that hindsight bias was controlled by ethical leadership to alleviate organizational cynicism. Fourth, it was found that leader machiavellianism was moderated by ethical leadership in the interaction with hindsight bias to alleviate organizational cynicism. Therefore, this study suggests new implications from the point of view of the existing research and future research tasks and direction on the role of leader, by deeply examining mechanisms between leader machiavellianism, hindsight bias and organizational cynicism. tasks and limitations on the role of leaders.