A UV light emitting diode comprising: a first conductivity type semiconductor layer ; a first stress adjustment layer disposed on the first conductivity type semiconductor layer , and including a first nitride layer including Al and a second nitride layer disposed on the first nitride layer and having a lower Al composition ratio than the first nitride layer ; an active layer disposed on the first stress adjustment layer ; and a second conductivity type semiconductor layer disposed on the active layer , wherein the first stress adjustment layer includes an Al delta layer inserted in the first nitride layer , and a lower surface of the first nitride layer in which the Al delta layer is inserted has greater average tensile stress than a lower surface of the second nitride layer directly disposed on the first nitride layer in which the Al delta layer is inserted; and wherein the first stress adjustment layer has a multilayer structure in which the first nitride layer and the second nitride layer are repeatedly stacked one above another, and includes the Al delta layer inserted in at least one first nitride layer among the first nitride layers , and the Al delta layer has a higher Al composition ratio than the first nitride layer in which the Al delta layer is inserted; wherein the Al delta layers are inserted in some of the first nitride layers and a distance between the Al delta layers gradually decreases in a direction toward the active layer , or the Al delta layer has a gradually increasing Al composition ratio in a direction from the first conductivity type semiconductor layer to the active layer . a first conductivity type semiconductor layer ; a first stress adjustment layer disposed on the first conductivity type semiconductor layer , and including a first nitride layer including Al and a second nitride layer disposed on the first nitride layer and having a lower Al composition ratio than the first nitride layer ; an active layer disposed on the first stress adjustment layer ; and a second conductivity type semiconductor layer disposed on the active layer , wherein the first stress adjustment layer includes an Al delta layer inserted in the first nitride layer , and a lower surface of the first nitride layer in which the Al delta layer is inserted has greater average tensile stress than a lower surface of the second nitride layer directly disposed on the first nitride layer in which the Al delta layer is inserted; and wherein the first stress adjustment layer has a multilayer structure in which the first nitride layer and the second nitride layer are repeatedly stacked one above another, and includes the Al delta layer inserted in at least one first nitride layer among the first nitride layers , and the Al delta layer has a higher Al composition ratio than the first nitride layer in which the Al delta layer is inserted; wherein the Al delta layers are inserted in some of the first nitride layers and a distance between the Al delta layers gradually decreases in a direction toward the active layer , or the Al delta layer has a gradually increasing Al composition ratio in a direction from the first conductivity type semiconductor layer to the active layer . <EOS>