In this paper, I study Eison's 叡尊 (1201-1290) understanding of the precepts on the basis of writings by three people: Genrin 元輪 (1278-87), Josen 定泉 (1273-1310-), and Eishin 英心 (1263-1310-) who belonged to the Eison lineage. Eison's understanding of the precepts will be consolidated in the following points. (1) Laymen who receive precepts through Betsuju 別受 are permitted to divide them and observe some of them and/or to delimit time to observe some of them. (2) Even if laymen violate precepts, those who receive precepts through Tsuju 通受 are guiltless. (3) For Buddhist priests, the working of avijñapti (kaiai) is strengthened because priests who receive the precepts through tsuju swear to live as bodhisattvas. However, the same crime as the Hinayana is applied when precepts are violated. As mentioned above, Eison reformed the understanding of the precepts for people with a weak relation to Buddhism, in order to to construct the system that gives the people precepts by priests who are bodhisattvas, and makes laymen's Buddhism more acceptable to them.