A thin film transistor array panel includes a gate line disposed on a substrate, the gate line including a gate electrode, a gate insulating layer disposed on the gate electrode, a semiconductor layer disposed on the substrate, the semiconductor layer including an oxide semiconductor, a data line disposed on the substrate and crossing the gate line, a data line layer including a source electrode connected to the data line and a drain electrode facing the source electrode, and a passivation layer covering the source electrode and the drain electrode. The data line layer includes copper or a copper alloy, and the semiconductor layer includes a copper doped oxide semiconductor. A content of copper doped on the oxide semiconductor is 0.2% to 0.82%.