An organic light-emitting device including a first electrode; a second electrode; emission units stacked between the first electrode and the second electrode and including at least one emission layer; and charge generation layers between two adjacent emission units, the charge generation layers each including 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 includes a first compound and a metal-containing material, the first compound being represented by Formula 1, the p-type charge generation layers include an amino group-free compound, at least one of the emission units further includes a hole transporting (HT)-emission auxiliary layer on a first electrode side thereof, and the HT-emission auxiliary layer includes at least one second compound, the second compound being represented by Formula 2: