To reinforce power supply wirings without sacrificing the interconnectivity of semiconductor devices. When three wirings are formed in parallel in the same wiring layer and the center wiring among them is shorter than the outer wirings, a projecting portion integrated into the outer wiring is formed utilizing a free space remaining on the extension of the center wiring. For example, when the outer wirings are used as power supply wirings, the power supply wirings can be reinforced by adding the projecting portion. At this time, because the projecting portion is arranged in the free space, the interconnectivity is not sacrificed.