According to one embodiment, a liquid crystal optical element includes an optical waveguide including a first main surface and a second main surface opposed to the first main surface, a first alignment film disposed on the second main surface, a first liquid crystal layer which overlaps the first alignment film, which comprises a first cholesteric liquid crystal, and which reflects at least part of light incident through the optical waveguide toward the optical waveguide, a second alignment film which overlaps the first liquid crystal layer, and a second liquid crystal layer which overlaps the second alignment film, which comprises a second cholesteric liquid crystal, and which reflects at least part of light incident through the optical waveguide toward the optical waveguide.