In an optical transmitter, a light-emitting device, a modulator that outputs a differential modulation current via alternating current coupling capacitors to an anode terminal and a cathode terminal of the light-emitting device, a first current source between the cathode terminal and a ground line (GND) of the light-emitting device, and a second current source between the anode terminal and a power source line (Vcc) of the light-emitting device, are provided.