A thin film transistor array panel includes a source electrode and a drain electrode on an insulating substrate, an oxide semiconductor on the insulating substrate and overlapping the source electrode and the drain electrode, a passivation layer overlapping the oxide semiconductor and on the insulating substrate, a gate electrode on the passivation layer, and a pixel electrode connected to the drain electrode. The gate electrode and the pixel electrode include a same material. The oxide semiconductor is between the source electrode and the gate electrode, and between the drain electrode and the gate electrode in a cross-sectional view of the thin film transistor array panel.