The disclosure provides an organic light-emitting device. The organic light-emitting device includes a substrate, and an organic light-emitting pixel array disposed on the substrate. The organic light-emitting pixel array includes a plurality of pixels. Each pixel includes a first sub-pixel and a second sub-pixel. Each sub-pixel includes a first electrode, an organic light-emitting element, a second electrode, and an optical path adjustment layer. The optical path adjustment layer is disposed between the first electrode and the second electrode. Particularly, the thickness of the optical path adjustment layer of the first sub-pixel is substantially equal to the thickness of the optical path adjustment layer of the second sub-pixel.