A display device includes a substrate, a first display element which is disposed on the substrate, and a plurality of diffraction patterns which are disposed on a path of light emitted from the first display element and arranged along a direction with a first period. when a width of a cross section of one of the plurality of diffraction patterns is defined as a first length, the first period and the first length satisfy Inequality (1): 0.4≤d1/DP1≤1,  (1) where DP1 is the first period, and d1 is the first length.