To provide a method for manufacturing a wiring, a conductive layer, a display device, and a semiconductor device, each of which can meet a large sized substrate and which is manufactured with a higher throughput by using a material efficiently, the conductive layer is formed over the substrate having an insulating surface by discharging the conductive material, and heat treatment is performed by a lamp or a laser beam over the conductive layer. Furthermore, the conductive film is formed under reduced pressure according to the present invention.