An object of the present invention is to provide an organic semiconductor composition, which improves the insulation reliability of an organic thin-film transistor without greatly reducing the mobility of the organic thin-film transistor, an organic thin-film transistor which is prepared by using the organic semiconductor composition, and electronic paper and a display device which use the organic thin-film transistor. The organic semiconductor composition of the present invention contains an organic semiconductor material (A) and a polymer compound (B) containing a repeating unit represented by the following Formula (B).