A method for fabricating an oxide thin film transistor includes sequentially forming a gate insulating film, an oxide semiconductor layer, and a first insulating layer; selectively patterning the oxide semiconductor layer and the first insulating layer to form an active layer and an insulating layer pattern on the gate electrode; forming a second insulating layer on the substrate having the active layer and the insulating layer pattern formed thereon; and selectively patterning the insulating layer pattern and the second insulating layer to form first and second etch stoppers on the active layer. The oxide semiconductor layer may be a ternary system or quaternary system oxide semiconductor comprising a combination of AxByCzO (A, B, C=Zn, Cd, Ga, In, Sn, Hf, Zr; x, y, z≧0).