An organic light-emitting device comprising a first electrode; a second electrode; emission units stacked between the first electrode and the second electrode and comprising at least one emission layer; and charge generation layers between two adjacent emission units, the charge generation layers each comprising an n-type charge generation layer and p-type charge generation layer, a maximum emission wavelength of light emitted by at least one of the emission units is different from that of another emission unit, one n-type charge generation layer comprises a first compound and a metal-containing material, the first compound being represented by Formula 1, the p-type charge generation layers comprise an amino group-free compound, at least one of the emission units further comprises a hole transporting (HT)-emission auxiliary layer on a first electrode side thereof, and the HT-emission auxiliary layer comprises at least one second compound, the second compound being represented by Formula 2: