Instead of forming contact holes the same way in both the non-image forming peripheral area (PA) and the image forming display area of a thin film transistor array panel, contact holes in the DA are formed to be substantially smaller than those in the PA for thereby improving an aperture ratio of the corresponding display device. In an exemplary embodiment, an inorganic gate insulating layer is not etched in the DA and only an inorganic first passivation layer among inorganic insulating layers positioned in the DA is etched to allow communication between the drain electrode and the corresponding field generating electrode. On the other hand, in the peripheral area, plural inorganic insulating layers such as the gate insulating layer, the first passivation layer, and the second passivation layer positioned on the gate wire and the data wire are simultaneously etched to form second contact holes and third contact holes exposing respective gate pads and data pads.