The present invention provides a technique by which a component forming a display device, such as a wiring can be formed with good adhesion.In the invention, a component forming a thin film transistor, a display device, or the like is formed with a material which is the same as at least one of the substances forming the formation subject surface added (mixed); thus, adhesion between the component and the formation subject is improved. An insulating layer formed over the component is formed with a laminate of a first insulating layer containing an organic material and a second insulating layer containing an inorganic material; thus, the insulating layer sufficiently covers irregularities on the surface of the component, and is also dense enough so as to be reliable as an insulating layer.