The present invention provides a method for forming a wiring having a minute shape on a large substrate with a small number of steps, and further a wiring substrate formed by the method. Moreover, the present invention provides a semiconductor device in which cost reduction and throughput improvement are possible due to the small number of steps and reduction of materials and which has a semiconductor element with a minute structure, and further a manufacturing method thereof. According to the present invention, a composition including metal particles and organic resin is irradiated with laser light and a part of the metal particles is baked to form a conductive layer typified by a wiring, an electrode or the like over a substrate. Further, a semiconductor device having the baked conductive layer as a wiring or an electrode is formed.