Provided is a method of fabricating a semiconductive oxide thin-film transistor (TFT) substrate. The method includes forming gate wiring on an insulation substrate; and forming a structure in which a semiconductive oxide film pattern and data wiring are stacked on the gate wiring, wherein the semiconductive oxide film pattern is selectively patterned to have channel regions of first thickness and source/drain regions of greater second thickness and where image data is coupled to the source regions by data wiring formed on the source regions. According to a 4-mask embodiment, the data wiring and semiconductive oxide film pattern are defined by a shared etch mask.