From the mid-1980's, the discussion of corporate governance has been still developed critically. It may be believed that this developments have helped the nations of world to improve their national wealth and to their competitive power. Nevertheless, corporate scandals, like Enron and WorldCom, has repeatedly happened over the world. That is not why the study on corporate governance is inefficient or insufficient. The answer about these problems is that entrepreneurship is rotten and corrupt because of deregulation of directors and CEOs. For example, the business judgement rule and the exculpation provision protected the authority of directors and officers, but decreased the wealth of shareholders and interests of corporations. Therefore, we need to balance between the accountability and authority of directors and officers. In 2002, 107th Cong. 60, Alan Greenspan Chairman of Federal Reserve Board said “The state of corporate governance to a very large extent reflects the character of the CEO and this is a very difficult issue to address. Although we may not be able to change the character of corporate officers, we can change behavior through incentives and penalties. That, in my judgment, could dramatically improve the state of corporate governance.” The meaning of his statement is equivalent to the opinions, which are held in Disney case in 2006. Disney case raised some questions about the fiduciary duty that comprised of dual duties, duty of care and duty of loyalty. It is held in Disney case that the fiduciary duty is the triads of duty - care, loyalty and good faith. The explicit recognition of the duty of good faith is an important development in corporate law. According to the holding of Disney case, although there are views in opposition to Disney case, corporate managers owe a fiduciary duty of good faith in addition to their traditional duties of care and loyalty. The duty of good faith in corporate law is comprised of a general baseline conception and specific obligations that instantiate that conception. The duty of good faith plays a four important role in corporate law. Fisrt, the duty of good faith covers managerial conduc that is improper but falls outside the spheres of the duties of care and loyalty. Second, certain rules that limit the duties of care and loyalty should not and do not apply to conduct that lacks good faith. Third, the duty of good faith characteristically functions differently from the duties of care and loyalty. Fourth, the Duty of good faith provides the courts with a principled basis for articulating new specific fiduciary obligations in response to social changes. Moreover, the duties of care and loyalty characteristically function as platforms for liability rules, while the duty of good faith characteristically functions as a condition to the application of rules that do not in themselves impose liability.