Provided are a resin composition and a substrate that are capable of being used for manufacturing an electronic device having excellent light extraction efficiency. The resin composition contains a polymer and a solvent dissolving the polymer. The resin composition is used to form a layer, and when refractive indexes of the layer along two perpendicular in-plane directions thereof are respectively defined as "Nx" and "Ny" and a refractive index of the layer along a thickness direction thereof is defined as "Nz", Nx, Ny and Nz satisfy a relationship of "(Nx+Ny)/2-Nz" > 0.01. Further, a method of manufacturing the electronic device by using such a substrate, and the electronic device are also provided.