King Munjong(文宗), the eleventh King of the Goryeo Dynasty, was the son of King Hyeonjong(顯宗), the eighth king, and the younger stepbrother(異母弟) of King Jeongjong(靖宗), the 10th king. Although King Jeongjong had four sons, he abdicated the throne to King Munjong. King Taejo(太祖) had opened the possibility for sons other than the eldest son to succeed to the throne. When King Jeongjong died, his sons were children under the age of 10 years. In the early period of the Goryeo Dynasty, when kings had young sons, there were precedents of abdicating the throne to their grown-up younger brothers. In addition, King Jeongjong and Munjong had an identical blood background. During the period, Goryeo people also naturally accepted the fact that a former king's younger brother succeeded to the throne. In this background, King Munjong ascended the throne. However, King Munjong did not ascend the throne after identifying state affairs with politic power. Therefore, he needed to increase his authority as the king. Moreover, as the sons of King Jeongjong had grown up, they could stir up trouble in future succession to the throne. Therefore, King Munjong intended to concentrate power on himself and remove trouble in future succession to the throne by selecting his son as successor to the throne. After the installation of Wangtaeja(王太子, the Crown Prince), King Munjong expanded and organized Donggunggwan(東宮官, the establishment of Secretariat of Wangtaeja) and carried out various rituals related to Wangtaeja. The control system for Donggunggwan was completed institutionally in 1068. At this time, the newly organized Donggunggwan was operated as a miniature version of the central government office. In addition, the ritual for the installation of Taeja, which was held in 1054, complied with regulated procedures. After the ritual of the installation, a ceremony to congratulate on Jangheungjeol(長興節, the birthday of Wangtaeja) was held in 1056. In 1064, the wedding ritual of Taeja took place, and the ritual for Taeja regulated in Yeji(禮志) of "Goryeosa(高麗史)" was carried out. In addition, the installation of Wangtaeja was made known overseas, and the Taeja of Goryeo was proclaimed by the Kitan three times. Such various measures played an important role in strengthening the status of Taeja as the man of authority next to the king. Later, Taeja demonstrated his status as the man of authority following the king by participating in state affairs on behalf of King Munjong who was not able to move about freely in his later years.