An LD driver is disclosed, which improves the rising and falling times of the driving current for the LD. The LD driver includes an inverting amplifier, an emitter follower connected in down stream of the inverting amplifier, a driving transistor driven by the emitter follower, and a current-mirror circuit connected in series to the inverting amplifier. The mirror current generated from the current flowing in the inverting amplifier is provided to the output of the emitter follower served for discharging the input capacitance of the driving transistor.