Disclosed is a light emitting diode (LED) having an active region of a multiple quantum well structure in which well layers and barrier layers are alternately laminated between a GaN-based N-type compound semiconductor layer and a GaN-based P-type compound semiconductor layer. The LED includes a middle barrier layer having a bandgap relatively wider than the first barrier layer adjacent to the N-type compound semiconductor layer and the n-th barrier layer adjacent to the P-type compound semiconductor layer. The middle barrier layer is positioned between the first and n-th barrier layers. Accordingly, positions at which electrons and holes are combined in the multiple quantum well structure to emit light can be controlled, and luminous efficiency can be enhanced. Furthermore, an LED is provided with enhanced luminous efficiency using a bandgap engineering or impurity doping technique.