This article aims at explaining the eunuches' buddhism promotion policies and their political power within the royal authority. King Maeng-Jong(明宗)could not control his King power wholly because the relatives of his mother's side had dominated all the royal authorities. Specially MuJeongDaeBi(文定大妃), the King's mother, had stronger than the King. She helped Park Han-Jong(朴漢宗), one of the eunuches, dominate all the authority in the dynasty. She appointed him as the Naesusa's head(내수사제조) that controlled all the royal palace finances. And he could control all the agricultural field within the office. On the while, Naesusa's head Park also controlled the agricultural fields which had been provided through buddhist's temple to obtain royal palace finances. Now because Naesusa's head could control all the temple agricultural fields, he also recommended and introduced Bowoo(普雨), a buddhist monk to MuJeongDaeBi. And so, at that time, Buddhism was thriving in the dynasty. On the conclusion, I think, in this un-proper political arrangement, that Buddhism was prosperous and its origin was derived from the enhancement of the eunuches and their promoter MuJeonhDaeBi's dominance in power struggle.