A series of cytochalasins (1–6), including a new one (1), were isolated from the ethyl acetate extract of the solid-state fermented rice culture of the fungus Phomopsis sp. cib-109. In this study, we investigated the secondary metabolites of the plant pathogenic fungus P. sp. cib-109 by chromatographic and spectroscopic methods. As a result, a new compound named cytochalasin R1 (1), along with epoxycytochalasin J, cytochalasin H, cytochalasin J, cytochalasin N, and cytochalasin O [9–13], were isolated and identified. The structure of compound 1 was elucidated to be 21-acetoxy-6,7,18-trihydroxy-5,6,16,18-tetramethyl[11]cytochalasa-13,19-trans-dien-1-one (cytochalasin R1) on the basis of spectroscopic analysis. Here we report on the structural elucidation of compound 1.