An optical modulation device includes: a Mach-Zehnder modulator including a semiconductor waveguide; a plurality of phase modulators that are spaced from each other; a first amplifier that is coupledwith an input transmission line transmitting an electrical signal, has an input impedance substantially equal to a characteristic impedance of the input transmission line; a first interconnection thatis coupled to the first amplifier and transmits the electrical signal to a first end of one of the plurality of phase modulators that is provided on an input side of the Mach-Zehnder modulator; a second interconnection that is coupled to the first amplifier and transmits the electrical signal to a first end of the other of the plurality of phase modulators that is provided on an output side of the Mach-Zehnder modulator; and a plurality of termination resistors respectively coupled to second ends of the plurality of phase modulators.