A display device including an oxide thin film transistor (TFT) is disclosed. A nitride-based gate insulating layer of a gate pad area is etched when an oxide semiconductor layer of a pixel area is etched by using a half-tone mask, a metal layer is formed at a contact hole of the etched gate insulting layer, and then a passivation layer formed thereon is etched. Thus, an overhang of the passivation layer can be prevented from being generated when the gate insulating layer is etched, and accordingly, the fabrication process can be simplified.