In Shin Buddhist studies, Shinran’s understanding of the theory of buddha-nature and that of Shin sectarian scholars in the Edo period have been discussed in the same manner. However, there are noticeable theoretical developments in the understanding of the theory among Edo scholars. In this paper, I compare Shinran’s discussions of buddha-nature in his writings and the most representative Shin Buddhist theory of buddha-nature developed in the Edo period by Dōshin (1773–1824) to identify their differences. In conclusion, I propose that the Shin Buddhist theory of buddha-nature developed in the Edo-Period should be treated as an expansion of Shinran’s understanding of buddha-nature. In order to understand why and how Shin sectarian scholars felt the need to expand Shinran’s understanding of buddha-nature, I also point out that further studies on Edo scholars awareness of the issues related to the buddha-nature theory as well as their socio-historical backgrounds are necessary.
