Light-emitting element drive apparatus

A light-emitting element drive apparatus for achieving light-emission control of a light-emitting element with high speed and high accuracy includes a monitoring photodiode 11 that receives light emitted from a laser diode 12 to generate a current, Im, that corresponds to the optical output thereof. The current Im is converted to a monitor voltage Vm by a current-to-voltage conversion circuit 13 , and its waveform is smoothed by a first low-pass filter 14 to produce a monitoring average value Vav that has a ripple component. A pre-modulated optical power setup voltage Vps generated by a variable direct-current voltage source 25 is modulated by a pulse modulation circuit 22 based on a data signal delayed by a predetermined time, and smoothed via a second low-pass filter 23 and a third low-pass filter 24 . Then, an optical power setup voltage Vref that has a nearly similar amplitude and ripple component is generated in synchronization with the average value Vav.