Abstract: A wiring substrate includes an insulating layer, an upper wiring pattern, and a lower wiring pattern, the wiring patterns sandwiching the insulating layer. The lower wiring pattern includes an interlayer connecting conductor integral therewith and projecting toward the upper wiring pattern for electrical connection to the upper wiring pattern. The interlayer connecting conductor is joined to the upper wiring pattern so as to penetrate into the upper wiring pattern beyond a joining interface between the insulating layer and the upper wiring pattern. Thus, the wiring substrate adaptable for a large current is provided without causing degradation of reliability in connection, which may occur by cracking, disconnection, interlayer peeling-off, etc.