In a laser beam processing apparatus that processes a semiconductor wafer having a multi-layered wiring structure formed thereon, scribe lines defined thereon, and at least one alignment mark formed on any one of the scribe lines, a laser beam generator system generates a laser beam, and a movement system relatively moves the semiconductor wafer with respect to the laser beam such that the semiconductor wafer is irradiated with a laser beam along the scribe lines to partially remove the multi-layered wiring structure from the semiconductor wafer along the scribe lines. An irradiation control system controls the irradiation of the semiconductor wafer with the laser beam along the scribe lines such that the alignment mark is left on the scribe line.