An optical device includes a display panel displaying an image and an optical modulation device that includes a first plate and second plate disposed to face each other and a liquid crystal layer disposed between the first plate and the second plate and including a plurality of liquid crystal molecules, wherein the first plate includes a plurality of lower electrodes extending in a first direction and arranged in a second direction crossing the first direction and the second plate include and an upper electrode. When the display panel displays a first image during a first subframe, the optical modulation device applies a first driving signal to the plurality of lower electrodes, and when the display panel displays a second image during a second subframe following the first subframe, the optical modulation device applies a second driving signal different from the first driving signal to the plurality of lower electrodes.