A light-emitting diode includes an N-type cladding layer, and a superlattice structure, an active layer, a P-type electron-blocking layer, and a P-type cladding layer disposed on the N-type cladding layer in such order. The superlattice structure includes at least one first layered element which has first, second, and third sub-layers that are stacked on one another in a direction away from the N-type cladding layer. The first, second, and third sub-layers have energy band gaps Eg1, Eg2, and Eg3 which satisfy a relationship of Eg1