Abstract: An optical control device comprises optical waveguides provided on a substrate having an electrooptic effect, a buffer layer provided on the substrate to cover the optical waveguides, and control electrodes provided on the buffer layer for applying a predetermined voltage across the optical waveguides. The optical waveguides has a coupling portion, at which an interval of the optical waveguides is narrowed. In this optical control device, a distortion dispersing structure is provided in the vicinity of the control electrodes to disperse distortion locally accumulated in the vicinity of the control electrodes to the whole area of the substrate uniformly.