Provided are a compound for thermally activated delayed fluorescence having a molecular aspect ratio of 1.5 or more, represented by the following Formula 1 and an organic electroluminescence device including the same in an emission layer. The organic electroluminescence device includes a first electrode, a hole transport region disposed on the first electrode, an emission layer disposed on the hole transport region, an electron transport region disposed on the emission layer, and a second electrode disposed on the electron transport region.