A long-wavelength light emitting device is disclosed. The long-wavelength light emitting device comprises: a first conductive semi-conductor layer; an active layer that is located on the first conductive semi-conductor layer and that has a quantum well structure; and a second conductive semi-conductor layer that is located on the active layer. The active layer comprises: one or more well layers including a nitride-based semi-conductor having 21% or more In; two barrier layers located in upper and lower parts of the well layers, and located between the well layers and the barrier layers, wherein the upper capping layers have a bigger band-gap energy relative to the barrier layers, and the upper capping layers and the well layers are in contact.