An optical pulse generator of simple constitution being able to generate a pulse train formed of short optical pulses is provided. The optical pulse generator includes an optical modulator 10 which modulates the incident light on one end face 1a thereof and outputs the light modulated thereby from the other end face 1b thereof, and an optical phase adjuster 20 which is optically connected with the other end face 1b of the optical modulator 10, adjusts the phase of the modulated light from the other end face 1b, and again receives the modulated light of which the phase has been adjusted, through the other end face 1b.