According to one embodiment, in a display device, a display substrate includes color filters of a plurality of colors arranged in a display area. The color filters are arranged in different colors alternately in a first direction and the same colors in a second direction orthogonal to the first direction. A first separation substrate separates wavelength light from received backlight according to the arrangement of the colors in the first direction, and outputs the separated light to a second separation substrate. The second separation substrate separates wavelength light from the received light from the first separation substrate according to the color of each row in the second direction, and outputs the separated light to the display substrate.