A group III nitride semiconductor light emitting element includes an active layer between an n-type layer and a p-type layer, having an n-electrode on the n-type layer and a p-electrode on the p-type layer, and having a mesa structure containing the p-type layer. In a top view of the group III nitride semiconductor light emitting element, the distance between a portion of an end part of the mesa structure and the periphery of the p-electrode is ⅓ or more of a diffusion length Ls.