A modulator including: a Mach-Zehnder modulator that includes an optical waveguide disposed on a substrate, the optical waveguide including an electrode thereon; a resin layer disposed on the substrate, the resin layer embedding the optical waveguide, the resin layer having a groove arranged besides the optical waveguide; a termination resistor disposed on the substrate in the groove of the resin layer; and a first wiring disposed on the resin layer, the first wiring being connected to the termination resistor and the electrode of the optical waveguide.