A semiconductor device including a gate electrode, a gate insulating layer, source/drain electrodes, and a channel-forming region that are disposed on a base is provided. The method includes the steps of forming a thin film by application of a mixed solution including a polymeric insulating material and a dioxaanthanthrene compound represented by structural formula (1) below; and subsequently drying the thin film to induce phase separation of the polymeric insulating material and the dioxaanthanthrene compound, thereby forming the gate insulating layer from the polymeric insulating material and the channel-forming region from the dioxaanthanthrene compound: wherein at least one of R3 and R9 represents a substituent other than hydrogen.