To obtain narrow optical pulses while suppressing ringing in pulses on the whole.

An optical pulse generating system, equipped with a Mach- Zehnder modulator (3) which is so provided as to modulate a light signal and a driving generator (4) which drives a Mach-Zehnder modulator (3) by driving a signal including a sinusoidal component of frequency (f/2) a half as high as a given repetition rate (f), generates optical pulses (OS) of the specified repetition frequency and is characterized in that the driving generator has networks (4'3,..., 4'2n+1) which each generate at least one odd harmonic of the sinusoidal component and synthesize, in addition to the sinusoidal component, the odd harmonic of the sinusoidal component with the driving signal.