Abstract: The present disclosure relates to a device for modulating light emitted by a laser, including an optical substrate that has an electro-optical effect, at least one optical waveguide formed near a front face of the optical substrate, a first electrode that is formed with a conductive transparent film so that a part of the optical waveguide may be covered and is used for applying an electric field to the optical waveguide, a second electrode that is paired with the first electrode and is used for applying an electric field to the optical waveguide, and a third electrode that is formed with a metal film in a position that is shifted from a position just above the optical waveguide and is electrically connected with the first electrode.