An electronic device is provided and includes a wiring structure including a conductive wiring and an insulating layer. The conductive wiring is disposed on a substrate and has a top side and two side walls opposite to each other. The insulating layer wraps around the conductive wiring at least through the top side and two side walls, wherein there is a gap between the insulating layer and at least one of the two side walls. The conductive wiring includes a first layer, a second layer and a third layer, the second layer is disposed between the first layer and the third layer, and the first layer is disposed between the second layer and the substrate. A thickness of the second layer is greater than a thickness of the first layer, and the thickness of the second layer is greater than a thickness of the third layer.