The disclosure is a method of manufacturing a nitride semiconductor laser wherein a plurality of crystal layers made of group III nitride semiconductors, including an active layer, are successively stacked on an underlayer. The method includes the steps of forming the plurality of crystal layers on the underlayer formed on a substrate, forming an electrode layer on the outermost surface of the crystal layers, plating a metal film onto the electrode layer, irradiating an interface between the substrate and the underlayer with light through the substrate toward so as to form a region of decomposed substances of the nitride semiconductor, delaminating the underlayer that supports the crystal layers from the substrate along the decomposed substance region, and cleaving the underlayer with the crystal layers so as to form cleaved planes constituting a laser resonator.