In recent years, we are facing with a serious problem of the market-capitalist system caused by immorality and unethical practice of leaders who have led capitalism. This research analyzes the effectiveness of authentic leadership which has emerged recently as one of the most interesting fields in leadership studies. It selects South Korea as the empirical case study. Researchers on authentic leadership have pointed out the limitation of traditional leadership theories which only concentrating on the skill and style of leaders. They also insist that authentic leaders can make a greater contribution to both long-term and short-term performance than any other types of leaders. In this research, we define authentic leadership as 'a very basic, genuine element and a root construct of positive leadership.' Authentic leaders are sincere to themselves and exhibit behavior positively and transform or develop associates into leaders themselves. An authentic leader mainly shows two kinds of character which are self-awareness and self-regulation. Selfawareness is the starting point of authentic leadership and it means that leaders know mission,visions, identity, emotions, motives, and values of leader themselves and their organizations. And authentic leaders also need to be fully aware of themselves. Self-regulation is a kind of self-control mechanism where authentic leaders try to reduce discrepancies between the actual-self and ideal-self. Self-regulation of authentic leadership helps the leader to endure the external influence and pressure. To verify the effect of authentic leadership, authors compare the effects of transformational leadership on team effectiveness. Although the primary purpose of this study is to test persuasiveness of the authentic leadership theory, we also try to analyze the effect of transformational leadership at the same time as it is well known for its universality in leadership studies. The results show that both leaderships have a positive effect on change-related performance(team performance and teaminnovativeness) and order-related performance (organizational commitment)and have a negative effect on perceived organizational politics. However, if the authentic leadership is controlled, the effect of transformational leadership on order-related performance(organizational commitment and perceived organizational politics) disappears. The effects of authentic leadership on team performance, whereas, team innovativeness, organizational commitment, and perceived organizational politics are all still significant. In conclusion, authors found the possibilities of authentic leadership in Korean firms and argue that various type of leaderships without authenticity could be just skills, gesture, and style of leaders. Even though transformational leadership has a strong effect on changerelated performance, we suggest that it is necessary to distinguish ‘pseudo’ transformational leadership from ‘authentic’ transformational leadership and their effect on team effectiveness. We also discussed the managerial implications of our claims.