Kamo no Chomei is well known as a Japanese medieval recluse. This paper is aimed at reading his essays Hojoki and Hosshinshu, and tries to rethink the relation between his reclusive life and poetry. The concept of reclusion for him was not necessarily related to how far he was removed from the capital nor what he did in his hermitage. Rather, the question was his state of mind, the extent to which his mind was detached from the usual worldly context motivated by interests, i.e. the Sphere (kyogai), such as social, political, and economical ones, that make people’s circumstances and by which their daily cognitions are shaped. On the other hand, according to his notion of transience (mujo), nothing is certain other than the fact that people sense and feel various things and move their hearts in various ways. Thus, what was crucial in his reclusive life was how he could deal with his mind and heart. In those respects, poetry was for him one of the most important elements on which to base his reclusive life, because poetry, it has been acknowledged, does not have any worldly purpose nor interest at all; it is barely to express how people’s hearts are moved.