A laser processing apparatus including a condenser having a function of spherical aberration. Since the condenser has a function of spherical aberration, the focal point of a laser beam to be focused by the condenser and applied to a wafer can be continuously changed in position along the thickness of the wafer. Accordingly, a uniform shield tunnel composed of a fine hole and an amorphous region surrounding the fine hole can be formed so as to extend from the front side of the wafer to the back side thereof, by one shot of the laser beam.