In a deep ultraviolet light-emitting device comprising a Group III nitride semiconductor, the concentrations of electrons and holes injected into a light-emitting layer is improved. A barrier layer has a last barrier layer closest to an electron blocking layer. The electron blocking layer has a first electron blocking layer closest to a light-emitting layer. The last barrier layer has a first position farthest from the first electron blocking layer, and a second position as an interface with the first electron blocking layer. The first electron blocking layer has a third position farthest from the last barrier layer. The Al composition ratio at the first position is higher than the Al composition ratio at the second position. The Al composition ratio at the third position is higher than the Al composition ratio at the first and second positions.