A light emitting unit of an electroluminescence device and a manufacturing method thereof are provided. The light emitting unit of the electroluminescence device includes a power line, a first electrode layer, a light emitting layer and a second electrode layer. The power line is on a substrate. The first electrode layer is disposed on the substrate and is electrically connected to the power line. In particular, a top portion of the first electrode layer has an oxygen concentration higher than that of a bottom portion of the first electrode layer. The light emitting layer is disposed on the first electrode layer and the second electrode layer is disposed on the light emitting layer.