Optical modulator driver circuit and optical transmitter

An optical modulator driver circuit (1) is provided with an amplifier (50, Q10, Q11, R10-R13), and a current amount adjustment circuit (51) capable of adjusting the amount of current in the amplifier (50) in accordance with a desired operation mode. The current amount adjustment circuit (51) comprises two or more current sources (IS10) capable of being individually turned on or off according to a binary control signal indicating the desired operation mode.