An active light emitting device disposed on a substrate is provided. The active light emitting device includes a scan line, a data line, a power line, a circuit unit, and a light emitting unit. The circuit unit is connected to the scan line, the data line, and the power line. The circuit unit at least includes an overlapping component which is at least partially overlapped with the power line. The light emitting unit is driven by the circuit unit. A light emitting region and a circuit region on the substrate are defined respectively by the light emitting unit and the circuit unit.