An organic light-emitting device comprises a first electrode, a second electrode disposed on the first electrode, a first organic light-emitting layer disposed between the first electrode and the second electrode, a second organic light-emitting layer disposed between the first organic light-emitting layer and the second electrode, a first charge generation layer (CGL) disposed between the first organic light-emitting layer and the second organic light-emitting layer, a second CGL disposed between the first CGL and the second organic light-emitting layer, and a first buffer layer disposed between the first CGL and the second CGL and including fullerene.