A liquid crystal optical device includes: a first electrode unit including a first substrate transparent to light, a light-transmitting layer formed on the first substrate, and a first electrode formed on the light-transmitting layer and being transparent to light, the light-transmitting layer including recesses formed on a surface facing the first electrode, arranged in a first direction, and extending in a second direction; a second electrode unit including a second substrate, the second substrate being transparent to light, and two second electrodes formed on the second substrate, the second electrodes being arranged in the second direction and extending along the first direction; a liquid crystal layer located between the first and second electrode units; a first polarizing plate located on an opposite side of the second electrode unit from the liquid crystal layer; and a drive unit that applies voltages to the first and second electrodes.