An undefill material is provided on the surface of a wafer in such a manner as to cover bumps, then the wafer is irradiated with a laser beam from the surface thereof and along planned cutting lines so as to remove an insulation layer and the underfill material present over the planned cutting lines, and the debris generated in this instance are deposited on the underfill material and are thereby prevented from being deposited on the wafer surface and/or on the bumps. Subsequently, a surface layer of the underfill material is cut so as to make the bumps flush in height and to expose the tips of the bumps.