A display device displaying two modes of two-dimensional images and three-dimensional images as mutually excluded alternatives depending on the alignment state of a liquid crystal region, comprising: a display element including spatially separated from each other a first region for generating the image signal for the right eye and a second region for generating the image signal for the left eye, and a liquid crystal lens panel, comprising: a lens layer comprising the liquid crystal region formed of liquid crystal molecules, wherein the liquid crystal region is convertible between a cholesteric alignment state having a focal distance according to Equation 2 of 0.1 mm to 100 cm, and a non-cholesteric alignment state: F = P 2 / 32 × d × Δn where P is a pitch of the liquid crystal region in the cholesteric alignment state, d is a thickness of the lens layer, and Δn is a difference (n e -n o) between an extraordinary refractive index (n e) and an ordinary refractive index (n o) of the liquid crystal molecule, wherein the liquid crystal molecules in the cholesteric alignment state form plural layers, and a director of an individual layer is aligned while being twisted along a helical axis, wherein the helical axis of the liquid crystal region in the cholesteric alignment state is aligned parallel to a surface of the lens layer, wherein the focal distance according to Equation 2 is with respect to linearly-polarized light perpendicular to the helical axis of the liquid crystal region in the cholesteric alignment state, wherein the UR region and UL region are alternately arranged in a plane, wherein at least one arrangement direction of those alternating regions is within said plane; wherein said arrangement direction and the helical axis direction are parallel to each other; and wherein the liquid crystal lens panel is arranged such that the image signals generated in a pair of the UR and UL regions are incident on a 1/2 pitch of the liquid crystal region in the cholesteric alignment state. a display element including spatially separated from each other a first region for generating the image signal for the right eye and a second region for generating the image signal for the left eye, and a liquid crystal lens panel, comprising: a lens layer comprising the liquid crystal region formed of liquid crystal molecules, wherein the liquid crystal region is convertible between a cholesteric alignment state having a focal distance according to Equation 2 of 0.1 mm to 100 cm, and a non-cholesteric alignment state: F = P 2 / 32 × d × Δn where P is a pitch of the liquid crystal region in the cholesteric alignment state, d is a thickness of the lens layer, and Δn is a difference (n e -n o) between an extraordinary refractive index (n e) and an ordinary refractive index (n o) of the liquid crystal molecule, wherein the liquid crystal molecules in the cholesteric alignment state form plural layers, and a director of an individual layer is aligned while being twisted along a helical axis, wherein the helical axis of the liquid crystal region in the cholesteric alignment state is aligned parallel to a surface of the lens layer, wherein the focal distance according to Equation 2 is with respect to linearly-polarized light perpendicular to the helical axis of the liquid crystal region in the cholesteric alignment state, wherein the UR region and UL region are alternately arranged in a plane, wherein at least one arrangement direction of those alternating regions is within said plane; wherein said arrangement direction and the helical axis direction are parallel to each other; and wherein the liquid crystal lens panel is arranged such that the image signals generated in a pair of the UR and UL regions are incident on a 1/2 pitch of the liquid crystal region in the cholesteric alignment state.