Disclosed is a thin film transistor array panel including: a substrate including a display area and a peripheral area; a second semiconductor layer disposed on the substrate, and disposed on a first semiconductor layer disposed in the display area and the peripheral area; and a passivation layer disposed on the first semiconductor layer and the second semiconductor layer, wherein the first semiconductor layer and the second semiconductor layer include an oxide semiconductor, and a thickness of the first semiconductor layer is different from that of the second semiconductor layer.