The wiring of the present invention has a layered structure that includes a first conductive layer (first layer) having a first width and made of one or a plurality of kinds of elements selected from W and Mo, or an alloy or compound mainly containing the element, a low-resistant second conductive layer (second layer) having a second width smaller than the first width, and made of an alloy or a compound mainly containing Al, and a third conductive layer (third layer) having a third width smaller than the second width, and made of an alloy or compound mainly containing Ti. With this constitution, the present invention is fully ready for enlargement of a pixel portion. At least edges of the second conductive layer have a taper-shaped cross-section. Because of this shape, satisfactory coverage can be obtained.