The present disclosure relates to a thin film transistor substrate having a metal oxide semiconductor for flat panel displays and a method for manufacturing the same. The present disclosure suggests a thin film transistor substrate including: a gate electrode on a substrate; a gate insulating layer covering the gate electrode; a source electrode overlapping with one side of the gate electrode on the gate insulating layer; a drain electrode being apart from the source electrode and overlapping with other side of the gate electrode on the gate insulating layer; an oxide semiconductor layer contacting an upper surface of the source electrode and the drain electrode, and extending from the source electrode to the drain electrode; and an etch stopper having the same shape with the oxide semiconductor layer, and contacting an upper surface of the oxide semiconductor layer.