In a nitride compound semiconductor light emitting device, an In.sub.0.3 Ga.sub.0.7 N/GaN multi-quantum well active layer 105 or an In.sub.0.1 Ga.sub.0.9 N/GaN multi-quantum well adjacent layer 104 is made as a saturable absorptive region so that self-pulsation occurs there. Thus, the device ensures self-pulsation with a high probability with a simple structure, and satisfies requirements for use as an optical head for reading data from an optical disc.