A method for producing a group III nitride semiconductor light emitting device which is a method for producing a group III nitride semiconductor light emitting device, in which a buffer layer composed of a group III nitride compound is laminated on a substrate and then an n-type semiconductor layer provided with an underlying layer, a light emitting layer, and a p-type semiconductor layer are sequentially laminated on the buffer layer, the method comprising:
- forming the buffer layer having a composition of AlxGa1-xN (0≦X<1) by activating, with plasma, and thereby reacting at least a metallic Ga source and a gas containing a group V element;
- and
- forming the underlying layer on the buffer layer,
- wherein the buffer layer is formed by a reactive sputtering method in which a gas containing a group V element is made to circulate inside a reactor.