In an optical device wafer processing method, a light emitting layer on the front side of a wafer is removed by applying a pulsed laser beam to the wafer along division lines from the back side of a substrate with the focal point of the beam set near the light emitting layer, thereby partially removing the light emitting layer along the division lines. A shield tunnel is formed by applying the beam to the wafer along the division lines from the back of the substrate with the focal point of the beam set near the front of the substrate. This forms a plurality of shield tunnels arranged along each division line, each shield tunnel extending from the front side of the substrate to the back side thereof. Each shield tunnel has a fine hole and an amorphous region formed around the fine hole for shielding the fine hole.