An organic electroluminescence display device is provided. The OEL device includes a substrate, a first electrode layer, a second electrode layer, an organic functional layer and at least one electrochromic medium layer. The first electrode layer is disposed on the substrate, the second electrode layer is disposed over the first electrode layer, and the organic functional layer and the electrochromic medium layer are disposed between the first electrode layer and the second electrode layer. Accordingly, the electrochromic medium layer is provided as a selective light valve to improve the reflection of the external light, and thus the contrast ratio of the organic electroluminescence display device is enhanced.