An optical sensing device includes a thin film transistor disposed on a substrate, an optical sensor, a planar layer, and an organic light emitting diode. The optical sensor includes a metal electrode disposed on a gate dielectric layer of the thin film transistor and connecting to a drain electrode of the thin film transistor, an optical sensing layer disposed on the metal electrode, and a first transparent electrode disposed on the optical sensing layer. The planar layer covers at least a part of the thin film transistor and the optical sensor. The organic light emitting diode is disposed on the planar layer. The anode electrode and the cathode electrode of the organic light emitting diode are electrically coupled to a gate line and a data line respectively.