The purpose of the study is to analyze the 'prohibition Law against Political- Nepotism' . so called Sang Pi Je(相避制), in terms of holding in check politlcal familism or bureaucratic collusion. While clique policy(朋黨政治) was developing, friction between king' s authority and minister's authority frequently happened. Sang Pi Jae carried out its function turning or mediation among their power and then it began in earnest usage as a effective system blocking off absurdity and irrationality of government official which was its original purpose. This was present situation which happened due to appearance of clique, the Nobilities(士林)' acceptance of desirable idea and emphasizing of holding of king' s authority. At that time the nobilities hoped that Chosun Dynasty worked as a theoretical ground in kingship policy(王道政治) through philosophical government ideology emphasizing ethics policy which built on the base toward ideal world. But as clique deepening, it happened that there was abuse emphasizing political position as a personal party rather than desire for nominalistic Kingship policy. Therefore, King faced to the situation searching for means governing efficiently because these specialization trend of minister's authority worked himself resonable burden in the national king' s position. So king in check political power trend of minister holding the right of personnel management which was the kernel function of authority. Therefore, in the period of clique policy(朋黨政治) a lot of political dispute like dispute for manner and political trouble like changing power frequently happened. Sang Pi Je' s administration got to cling to function arbitrate minister's right in those trend. But king' s mediating or tuning function through Sang Pi Jae didn't show considerable advance in effect because of limit opposition of clique, showed an aspect being bent fundamental confrontation as we know Hyeun Jong-Jo(顯宗朝)' s effort strengthening Sang Pi Je. These situation thanked to effort overcoming weakening of king' s authority as we see domination of maternal relation in Myeung Jong(明宗) times, excessive portliness of clique developed after Sun Jo(宣祖) times, and uneasy changing authority in In Jo(仁祖) times. And there happened situation which had to reform in operation. And then the situation developed toward direction enlarging these. These king' s using power appeared as the changing power leading competition among clique for strengthening king' s authority while opposition of between clique checking and clique leading political situation appeared in Suk Jong(蕭宗) times. At that time, Sang Pi Je was accomplished legislational consolidation by king' s powerful driving force impulse. And the former fundamental confrontation was overcome slowly.