Group iii nitride semiconductor light emission element

In a Group III nitride semiconductor light-emitting device which comprises a substrate (1) and a light-emitting layer (10) having a multiple quantum well structure comprising a barrier layer (11b 12b), which is provided on a surface of the substrate and formed of a Group III nitride semiconductor, and a well layer (11a, 12a) formed of an indium-containing Group III nitride semiconductor, the light-emitting layer is constituted by stacking a plurality of multilayer portions (11, 12) which comprise one unit multilayer portion (11m) comprising the well layer and the barrier layer or two or more stacked unit multilayer portions (12m). When the multilayer portion (12) comprises two or more unit multilayer portions (12m), the respective well layers or the respective barrier layers have the same thickness and composition, and in the respective multilayer portions (11, 12), the barrier layers (11b 12b) of the unit multilayer portions are different in thickness with respect to one another, and thereby, the Group III n