A wiring substrate includes a core portion and a wiring portion. The core portion includes a wiring layer and an organic resin core substrate. The wiring portion includes wiring layers and organic resin insulative layers. The wiring layer of the core portion is formed in a state in which the organic resin core substrate is supported by a support body. The wiring layers of the wiring portion are formed in a state in which the organic resin core substrate is adhered to a support body and the wiring layer of the core portion faces toward the support body.