A plurality of pixels is arranged periodically in the x-axis direction and the y-axis direction in the display panel of a display device, and because light is blocked by the portion other than the open part in each pixel, the display panel has a two-dimensional lattice structure. The pixels are rectangular, and the length Px of the long edges in the x direction is larger than the length Py of the short edges in the y direction. A louver, in which transparent regions and non-transparent regions are arranged periodically in a one-dimensional direction, is provided on the display panel, and the angle formed by the x axis and the one-dimensional period direction of the louver is 45 degrees or less, and preferably 10 degrees or less. This configuration makes it possible to obtain an optical element having high directivity, reduced moiré, and high transmittance. It is also possible to obtain a display device having excellent display quality into which the optical element is incorporated.