A group III nitride semiconductor light emitting device with a double sided electrode structure which has a low driving voltage as well as excellent light emission efficiency is provided, and the group III nitride semiconductor light emitting device includes at least an impurity layer 30 composed of a high concentration layer 3b made of a group III nitride semiconductor containing high concentration of impurity atoms, and a low concentration layer 3a made of a group III nitride semiconductor containing impurity atoms whose concentration is lower than that of the high concentration layer 3b; and a group III nitride semiconductor layer 2, and the lower concentration layer 3a and the high concentration layer 3b are continuously formed on the group III nitride semiconductor layer 2 in this order to form the group III nitride semiconductor light emitting device.