An X-ray detector includes; a panel having a plurality of photo-detecting pixels generating electrical signals in response to the detection of X-rays, a gate driver providing a gate signal to the plurality of photo-detecting pixels, wherein the photo-detecting pixels output the electrical signals in response to the gate signal, a readout integrated circuit reading out the electrical signal in response to the gate signal, a main board including a controller receiving the electrical signal and converting the electrical signal to an image signal, a film attached to the panel and the main board, the film including a signal line electrically connecting the readout integrated circuit to the panel and main board, wherein the readout integrated circuit is mounted on the film, and a shielding layer covering the film and comprising a conductive material, wherein the shielding layer prevents externally applied electromagnetic signals from passing through the film.