It is an object of the present invention to improve the surface planarity of a film by uniforming the thickness of an insulating layer. Further, it is another object of the invention to provide a technology for manufacturing an electronic device typified by a high-definition and high-quality display device with high yield at low cost with the use of the insulating layer. In a method for manufacturing a semiconductor device according to the invention, a semiconductor layer is formed; an insulating layer is formed over the semiconductor layer; a wiring layer connected to the semiconductor layer is formed in an opening provided in the insulating layer; and an electrode layer connected to the wiring layer is formed. The insulating layer is formed by spin coating with a composition containing an insulating material, which has a viscosity of from 10 mPas to 50 mPas.