To provide a method for manufacturing a peeling substrate, which can suppress the occurrence of a crack in a crystal material, and which enables the stable formation of a processing layer.SOLUTION: A method for manufacturing a peeling substrate comprises the steps of: forming a processing layer on a substrate 10, including a laser-focusing step of focusing a laser beam at a predetermined depth from a surface of the substrate 10, and a positioning step of performing a positioning action by relatively moving a laser beam-focusing part 160 with respect to the substrate 10; and preparing the peeling substrate by peeling the substrate 10 with the processing layer formed therein at the processing layer. The laser-focusing step includes a laser beam-adjustment step of using a diffractive optical element 170 serving to branch a laser beam into a plurality of branch laser beams to branch the laser beam so that at least one branch laser beam differs from the other branch laser beams in intensity. Using of the plurality of branch laser beams, a branch laser beam having a higher intensity, the processing layer is caused to extend to process the substrate 10; and the extension of the processing layer is suppressed by a branch laser beam having a lower intensity.SELECTED DRAWING: Figure 1