The present invention relates to an optical control device including an anisotropic dielectric substrate; and optical waveguides formed on the substrate so as to cause optical waves propagating through the optical waveguides to interact with electrical signals propagating through modulation electrodes. The modulation electrodes include a plurality of signal electrodes (21, 23) and a ground electrode disposed around the signal electrodes. The plural signal electrodes have respective electrode portions which are disposed in directions where the dielectric constant of the substrate is different. Signal electrodes ranging from signal input terminal portions of the signal electrodes to a point where the interaction between the electrical signals and the optical waves propagating through the optical waveguides starts are used as input-side signal electrode portions. The modulation electrodes including the plurality of signal electrodes have matched impedance, and the sum of effective electrode lengths of the input-side signal electrode portions, which are the products of physical electrode lengths and effective refractive indices of the electrical signals, is the same in each of the directions where the dielectric constant is different.