The present invention provides a wiring, a display device, and a method of manufacturing the same. A first metal diffusion-preventing layer is formed on a substrate or on a circuit element formed on the substrate. Then, a metal wiring layer is selectively formed on the first metal diffusion-preventing layer by an electroless metal plating method or a metal electroplating method. Further, the undesired portion of the first metal diffusion-preventing layer is removed. Finally, a second metal diffusion-preventing layer is formed selectively by an electroless metal plating method in a manner to cover the metal wiring layer or both a seed layer and the metal wiring layer.