A detecting device is provided. The detecting device includes a substrate, at least one transistor, at least one detecting element, and a scintillator layer. The transistor is disposed on the substrate. The detecting element is disposed on the transistor and electrically connects to the transistor. The detecting element includes a first electrode layer, a semiconductor layer, and a second electrode layer. The semiconductor layer is disposed on the first electrode layer, and the second electrode layer is disposed on the semiconductor layer. The scintillator layer is disposed on one side of the substrate, wherein at least one corner area of the scintillator layer has a curved structure or a chamfered structure.