A nitride semiconductor light-emitting device includes a laminate structure formed of a plurality of nitride semiconductor layers including a light-emitting layer, and having cavity facets facing each other, a first protection film made of AlN, formed over a light-emitting facet of the cavity facets, and a second protection film made of Al2O3 having a refractive index of n1, formed thereon. The second protection film has a crystallized surface at least in a region facing a light-emitting region on the cavity facets; the thickness (t) of the second protection film satisfies λ/(2·n1)