An optical modulator includes: a semiconductor chip; a waveguide in the semiconductor chip; a traveling wave electrode including an input portion and an output portion, to which a signal is applied for modulating light passing through the waveguide; a power supply line connected to the input portion via a first wire; and a termination resistor connected to the output portion via a second wire. Capacitance between the output portion and a grounding point is larger than capacitance between the input portion and the grounding point.