An optical modulation element configured by forming an optical waveguide on an optical element substrate and a polarization-combining part that combines light waves modulated in the optical modulation element are disposed in a housing. A plurality of lead pins are fixed to a side wall of the housing. Each of the plurality of lead pins has a protrusion portion protruding into an internal space of the housing and is electrically connected to the optical modulation element by bonding a wire to the protrusion portion. A loop shape of a wire that is bonded and connected to at least part of the lead pins among the plurality of lead pins is different from a loop shape of a wire that is bonded and connected to other lead pins.