A laser processing method of applying a pulsed laser beam to a single crystal substrate to thereby process the single crystal substrate. The laser processing method includes a numerical aperture setting step of setting the numerical aperture (NA) of a focusing lens for focusing the pulsed laser beam so that the value obtained by dividing the numerical aperture (NA) of the focusing lens by the refractive index (N) of the single crystal substrate falls within the range of 0.05 to 0.2, a positioning step of relatively positioning the focusing lens and the single crystal substrate in the direction along the optical axis of the focusing lens so that the focal point of the pulsed laser beam is set at a desired position in the direction along the thickness of the single crystal substrate, and a shield tunnel forming step of applying the pulsed laser beam to the single crystal substrate so as to focus the pulsed laser beam at the focal point set in the single crystal substrate thereby forming a shield tunnel extending between the focal point and a beam incident surface to which the pulsed laser beam is applied.