The present invention provides an optical element which prevents a contaminant component adhering to the edge thereof from spreading through the capillary action and thus from forming a stain; and a display device including the element. The present invention directs to an optical element including: a base material including a front surface provided with projected portions at a pitch equal to or shorter than the wavelength of visible light, and a side surface surrounding the front surface; and a covering material covering at least one of an edge of the front surface and the side surface, the covering material filling gaps between the projected portions. The present invention also directs to a display device including such an optical element.