A wafer has, on a front face thereof, a device region in which a device is formed in regions partitioned by a plurality of scheduled division lines. An outer peripheral region surrounds the device region. A reflecting film of a predetermined width is formed from the outermost periphery of the wafer on a rear face of the wafer corresponding to the outer peripheral region. The front face side of the wafer is held in a chuck table, and a focal point of a pulsed laser beam of a wavelength having permeability through the wafer is positioned in the inside of the wafer corresponding to the scheduled division lines. The pulsed laser beam is irradiated from the rear face side of the wafer to form modified layers individually serving as a start point of division along the scheduled division lines in the inside of the wafer.