The purpose of this paper is to understand the essential structure of rhythm in the process of a performance from the view point of homeodyamics, which produces the living state of organism: an unexplored field of performance analysis. Rhythm consists of two contradicting and yet cooperatative actions: to drive and to restrain. According to Nakai Shoichi, a scholar of aesthetics, to see a performance is to recognize something substantial of the world beyond ordinary life. This is possible because the dynamics of rhythm a spectator experiences during the performance reveals the essential aspect of the real world. For the analysis of dramatic rhythm, Yamazaki Masakazu's The Acting Mind and some of Kinoshita Junji's comments on houseback riding are quite suggestive. In the concluding part of the paper, this writer examines the dramatic rhythm in the scene between Oedipus and Teiresias in Sophocles' Oedipus Rex.