A liquid crystal optical element according to the present disclosure includes: a prism array composed of a plurality of prisms that have ridge lines extending in a first direction and are arranged in a second direction orthogonal to the first direction; a liquid crystal layer provided on the prism array; and an electrode via which a voltage is applied to the liquid crystal layer. When the voltage applied to the liquid crystal layer is 0 volt, long axes of liquid crystal molecules of the liquid crystal layer are oriented so as to be inclined at a predetermined angle relative to the first direction in a plane orthogonal to the second direction.