The present invention provides a composition for forming a gate insulating film, 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, electronic paper, and a display device. The composition for forming a gate insulating film of the present invention contains an insulating material and a migration inhibitor selected from the group consisting of a compound represented by any of Formulae (1) to (8), a polymer compound (X) containing a repeating unit represented by Formula (A), and a polymer compound (Y) containing a repeating unit represented by Formula (B) and a repeating unit represented by Formula (C).