A wiring structure includes a first wiring having a first wiring width, and a second wiring formed in the same layer as a layer in which the first wiring is formed, and having a second wiring width greater than the first wiring width. The second wiring is electrically connected to the first wiring. Both of the first and second wirings are composed of copper or an alloy predominantly containing copper therein. The first and second wirings have the same thickness as each other. A ratio of an area of the second wiring to an area of the first wiring is N:1 where N is equal to or greater than 2,000 and equal to or smaller than 200,000,000 (2,000N200,000,000).