In one embodiment, an array substrate for a flat display device includes a gate line extending in a first direction, a source line extending a in second direction orthogonally crossing the first direction. A switching element includes a semiconductor layer, a gate electrode electrically connected with the gate line, a source electrode electrically connected with the gate line in contact with the semiconductor layer and a drain electrode in contact with the semiconductor layer. An insulating film covers the source line and the switching element, and includes a contact hole exposing the drain electrode. A pixel electrode is formed on the insulating film. An insulating filling component is filled in the contact hole of the insulating film so as to be interposed between the drain electrode and the pixel electrode in a pixel in which the source line is short-circuited with the drain electrode.