A display device including a backlight module is provided. The backlight module includes: a substrate, a backlight cavity, a plurality of light emitting elements, and an optical adjustment layer. The backlight cavity is located on the substrate. The plurality of light emitting elements is disposed in the backlight cavity. The optical adjustment layer covers the plurality of light emitting elements and fills the remaining space of the backlight cavity. The optical adjustment layer has a refractive index n greater than the refractive index n0 of the air.