A wiring substrate includes an adhesive layer, a wiring layer, and a support substrate. The adhesive layer includes a first surface and a second surface that is opposite to the first surface. The wiring layer is formed on the first surface of the adhesive layer. The support substrate is formed on the second surface of the adhesive layer. The wiring layer is partially exposed in a through hole extending through the adhesive layer and the support substrate in a thicknesswise direction. The support substrate is adhered to the adhesive layer in a removable manner.