An organic semiconductor polymer having a structural unit represented by the following Formula (I), a composition for organic semiconductor material, a photovoltaic cell and a polymer, wherein X represents Si, S or O; R1 represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, an aromatic heterocyclic group or an oxygen atom; p represents 0, 1 or 2; herein, the bond between X and R1 is such that when X is Si, the bond is a single bond, and when X is S, the bond is a double bond. Furthermore, when X is O, p represents 0.