A wiring substrate includes a wiring substrate body and a stiffener. The latter is formed from a rolled metallic sheet and is bonded to a first main surface of the wiring substrate body. The stiffener has a boundary profile, in a plan view, which is substantially identical to that of the wiring substrate body, and a first direction of the boundary profile of the stiffener or the wiring substrate body intersects the rolling direction of the stiffener at an angle. This construction reduces the amount of deformation of the wiring substrate produced by bonding of the stiffener to the wiring substrate body and/or caused by temperature variations experienced by the construction. Because of this reduction in deformation, the wiring substrate provides improved reliability with respect to connections made to an electronic component mounted thereon as well as improved reliability with respect to connections made to another printed wiring board.