An X-ray detector panel comprises: a substrate; a transistor including a gate electrode disposed on the substrate, a gate insulating layer disposed on the gate electrode, an active layer disposed on the gate insulating layer, and a source electrode and a drain electrode disposed on the active layer and separated from each other; a photodiode including a first electrode connected to the drain electrode of the transistor, a photoconductive layer disposed on the first electrode, and a second electrode disposed on the photoconductive layer; an interlayer insulating layer including a first interlayer insulating layer covering the transistor and the photodiode, the first interlayer insulating layer being formed of an insulating material having a band gap energy of about 8 eV to about 10 eV; a data line disposed on the interlayer insulating layer and contacting the source electrode of the transistor via the interlayer insulating layer; a bias line disposed on the interlayer insulating layer and contacting the second electrode of the photodiode via the interlayer insulating layer; and a passivation layer disposed on the data line, the bias line, and the interlayer insulating layer.