A wiring substrate includes a wiring layer made of copper, an electrode layer made of copper, and an insulating layer arranged adjacent to the electrode layer. The wiring layer is stacked on the electrode layer and the insulating layer. The insulating layer and the wiring layer are stacked with an adhesive layer interposed between the insulating layer and the wiring layer. The electrode layer and the wiring layer are stacked with a copper alloy layer formed adjacent to the adhesive layer and interposed between the electrode layer and the wiring layer.