It is well known, that the shareholders in a corporation have also a fiduciary duty to the corporation and other shareholders. In U.S. and German jurisdiction, we can find many cases on the controlling shareholders’ fiduciary duty. The famous ‘Donahue v. Rodd Electrotype’ Case of the Massachusetts Supreme Court recognized the fiduciary relationship between the shareholders in a closely held corporation like in a partnership. The Delaware Chancery and Supreme Court released many useful cases on the law of controlling shareholders, in which the fair price had to be decided by court ruling. The German Federal Supreme Court released in 1988 the ‘Linotype’, the first german case, in which the court recognized the fiduciary duty of controlling shareholders in a German stock corporation. Seven years later the same court released the ‘Girmes’, where the court emphasized also the fiduciary duty of minority shareholders in a situation, where they can have a decisive role through their voting right. Judicial Courts in South Korea do not have any comparative cases on the same issue until now. But the Korean Commercial Code has recently established, after the 2011 revision, several legal institutes on the fiduciary duty of controlling shareholders (ss. 360-24, 398 etc). The fiduciary duty of controlling shareholders has played an important role especially in the following sections. First of all, the self-dealing between the controlling shareholder and company reveals a good example for conflicting transaction. Almost all the jurisdiction employes the entire fairness standard or requests preapproval by independent directors. Secondly, the institute of ‘de facto directors’ can be used for the controlling shareholders who actively intervene in corporate affairs. Thirdly, there are many cases of violating the shareholders’ fiduciary duty in a ‘going private’ transaction. In especially in the 1980s U. S., there were a number of ‘two tier front loaded tender offer’. Finally we can find a good example for the fiduciary duty of controlling shareholders in German Konzernrecht. The German law of corporate groups(Konzernrecht) has the most elaborate device. Corporate parents have the power to instruct their subsidiaries to follow group interests. They must indemnify for any losses that stem from acting in the group’s interest. The German law of corporate groups grants the subsidiaries the Ausgleichsanspruch (an indemnification right). The author is eagerly waiting for the first Korean case on the shareholder’s fiduciary duty.