This article will prove the transition and the organic relation of Jugonshi(呪禁師) and Onyoushi(陰陽師)`s task, from the perspective on decline of statue system(ritsuryo-sei; 律令制) in this thesis. In statue system, the administrative office which administered the almanac(冊曆)·astronomy·augur(占卜)·houjutsu(方術)·medicine was Onyouryou(陰陽寮) and Tenyakuryou(典藥寮). But yin and yang-thought had the tendency to be made bad use for the wrong political aims. So the statue-state(律令國家) restricted yin and yang-thought to be remained as a kind of method which controlled by the state. At that time, the officials worked for Onyouryou and Tenyakuryou was under the command of state bureaucracy system. The age the Fujiwara family(藤原氏) which had commanded the power to all around the political fields, had been maintained from middle of 9th century to late 11th century, which called "Sekkan politics(攝關政治)". In this time, despite statue-state had been seemed to have maintained externally, but the state politics had been ruled by the Fujiwara family, the Sekkanke(攝關家) in substance. It was so natural that the bureaucracy in that age could not be carried out in normal way. Onyouryou and Tenyakuryou as a state bureaucracy office, couldn`t have been run normally either. Ancient Japanese rulers made the post of Jugonshi in Tenyakuryou in the time they had settled a statue at the first. For they had expected the Jugonshi to carry out their medicine duty. The enlargement of tasks handled by Onyoushi brought the changes to administration of statue system. That is to say, along with slackness of statue-state system, they started to deal with the tasks concerned with the taboos such as monoimi(物忌), katatagae(方違) and medicines. Onyoushi started to take charge of the tasks never prescribed in state statutes. Onyoushi`s medicine is similar to that of Jugonshi`s. The cause of disease made clear by Onyoushi was kami, Buddha and ghost. In this case, they must had gotten rid of the causes of disease to heal their maladies by the way of many sorcerous rituals. A phenomenon to which we need to pay attention is the fact that in the period the tasks of Onyoushi increased, the existence of Jugonshi disappeared. Along with inquire into the change of Onyoushi`s functions, we could approach to the solution of this problem. In conclusion, Onyoushi and Jugonshi was two technique(技術)-officials based on the same philosophical thought and operated by state administration system. Afterwards, the medical tasks of Jugonshi had been absorbed into that of Onyoushi. The change of Onyoushi`s function and the disappearance of Jugonshi not only had resulted from the same base of philosophical thought, but also had relation with the similarity between the two posts(Onyoushi and Jugonshi), and political fluctuations.