An object of the present invention is to provide an organic semiconductor composition that may form an organic thin film transistor having excellent hysteresis characteristics while high carrier mobility is maintained. Another object of the present invention is to provide an organic semiconductor film, an organic thin film transistor, and a method of manufacturing an organic thin film transistor. An organic semiconductor composition according to the present invention includes: a compound X having a molecular weight of 2,000 or greater and having a repeating unit represented by Formula (1); and a low molecular weight compound Y represented by Formula (2).