An oxide semiconductor thin film transistor substrate includes a gate line and a gate electrode disposed on an insulating substrate, an oxide semiconductor pattern disposed adjacent to the gate electrode, a data line electrically insulated from the gate line, the data line and the gate line defining a display region, a first opening exposing a surface of the data line, a second opening exposing a surface of the oxide semiconductor pattern, and a drain electrode disposed on the first opening and a drain electrode pad, the drain electrode extending from the first opening to the second opening and electrically connecting the drain electrode pad and the oxide semiconductor pattern.