An optical device includes first and second substrates disposed opposite each other; a partition wall provided upright on an inner surface of the first substrate, facing the second substrate, and extending, to divide a region on the first substrate into cell regions arranged in a first direction, in a second direction different from the first direction; first and second electrodes disposed on wall surfaces of the partition wall to face each other in each of the cell regions; an insulation film; a third electrode provided on an inner surface of the second substrate facing the first substrate; a protruding section formed upright on the inner surface of the second substrate and dividing each of the cell regions into sub cell regions arranged in the second direction; and polarity and non-polarity liquids sealed between the first substrate and the third electrode.