To improve coupling reliability in flip chip bonding of a semiconductor device. By using, in the fabrication of a semiconductor device, a wiring substrate in which a wiring that crosses an opening area of a solder resist film on the upper surface of the wiring substrate has, on one side of the wiring, a bump electrode and, on the other side, a plurality of wide-width portions having no bump electrode thereon, a solder on the wiring can be dispersed to each of the wide-width portions during reflow treatment in a solder precoating step. Such a configuration makes it possible to reduce a difference in height between the solder on each of terminals and the solder on each of the wide-width portions and to enhance the coupling reliability in flip chip bonding.