In this paper, we discuss on the river conservancy policy to make river channels straight in middle Edo era. Firstly, a proposal contained in “KenkaRoku”(『献可録』「水は下より治ると申儀御尋に付申上侯」of Kyuso Muro (室鳩巣), a confucianist, is made clear the source of the thought. Secondly, the contents of the proposal is proved to be a misconstruction of the original literatures, Jia Rang's three policies of harnessing the Yellow River, concerning the river conservancy thought of old China.
