The present invention provides a method for producing a Group III nitride semiconductor light-emitting device, the device including a light-emitting layer which is formed so as to contour a stripe-pattern embossment and to have a uniform thickness. In the production method, firstly, a stripe-pattern embossment having a serrated cross section is formed on one surface of a substrate. Subsequently, on the surface of the substrate on the side of the stripe-pattern embossment having a serrated cross section, an n-type layer, a light-emitting layer, and a p-type layer are sequentially deposited through reduced-pressure MOCVD so as to contour the embossment. Thus, each of the layers is formed so as to contour the embossment, and to have a stripe pattern with a serrated cross section. In this MOCVD process, the direction of gas flow is parallel with the direction of the stripe of the embossment. Thus, the light-emitting layer has uniform thickness and composition in an in-plane direction.