A thin film transistor array substrate includes: a first conductive layer including first lines for transmitting data signals to the thin film transistors; a second conductive layer disposed on the first conductive layer and including second lines for supplying a driving voltage to the thin film transistors; a first insulating layer disposed between a semiconductor layer and the first conductive layer and including a first material layer; a second insulating layer disposed between the first conductive layer and the second conductive layer and including a second material layer having a dielectric constant greater than that of the first material layer; and a contact plug penetrating the second insulating layer and the first insulating layer, and connecting the second conductive layer to the semiconductor layer. A taper angle of the contact plug in the second material layer is greater than that of the contact plug in the first material layer.