An optical device wafer processing method for dividing an optical device wafer into a plurality of individual optical devices. The optical device wafer is composed of a substrate and a semiconductor layer formed on the front side of the substrate. The optical devices are partitioned by a plurality of crossing division lines formed on the semiconductor layer. The optical device wafer processing method includes a division start point forming step of applying a laser beam having a transmission wavelength to the substrate to the intersections of the crossing division lines in the condition where the focal point of the laser beam is set inside the substrate in an area corresponding to the intersections of the crossing division lines, thereby forming a plurality of crossing modified layers as division start points inside the substrate at the intersections of the crossing division lines; and a crack growing step of applying a CO2 laser beam along the division lines to grow cracks inside the substrate from the division start points.