This paper analyzed the background of the formation of the Imperial Bishops in Medieval Germany and their collective characteristics, paying close attention to the relationship between the king and the aristocracy. In addition, this paper attempted to analyze the influential role of Imperial Bishops on the political structure and state system of Germany before the Investiture Controversy. The Imperial Church System established by the Ottonian and Salian Dynasties, which was initiated by Otto Ⅰ ancl eventually became the official ruling system of Germany under Heinrich Ⅱ, largely contributed to the strengthening of the royal authority during the process of integrating the kingdom. The aristocracy`s traditional power over the church was restrained as a result of the king`s bestowment upon the Imperial Church of the right to exercise sovereign power over it`s activities. During the 10th and 11th centuries, the Imperial Bishops became the German kings` source of power. The bishops were able to become prominent by going beyond their religious roles and involving themselves in political and military affairs, in some instances even helping the king mobilize for war. The Holy Roman Empire was able to become the most powerful country in Western Europe because of their cooperation. As the dependence of kings on the Imperial Church increased, the appointment of bishops and abbots became more and more important. As such, the new indirect system of power centered on the Imperial Church began to erode the traditional direct ruling system based on the king. The event that shattered the cooperative system between the Imperial Church and kings was the implementation of the Monastic Reforms and the Investiture Controversy. While for a long time the sacredness of the king served as the essential factor guaranteeing the existence of the Imperial Church, the Reformer, who sought to separate church and state into secular and religious spheres, began to shake the Imperial Church System to its very foundation.