According to one embodiment, a liquid crystal optical device includes first and second substrate units and a liquid crystal layer. The first substrate unit includes a first substrate having a first surface and a first side extending in a first side direction, and first electrodes provided on the first surface. The second substrate unit includes a second substrate having a second surface, and second electrodes provided on the second surface. The liquid crystal layer includes liquid crystal molecules provided between the first and second substrate units. A first angle in a first rotation direction from the first side direction to the first direction is less than 90 degrees and more than 0 degrees. A second angle in the first rotation direction is different from the first angle. A third angle in the first rotation direction is different from the first and second angles.