A thin film transistor array panel includes a substrate; a gate electrode formed on the substrate; a data line formed on the substrate; a gate insulating layer formed on the data line and the gate electrode, and having a first contact hole exposing the gate electrode, and a second contact hole exposing the data line; a gate line intersecting the data line, and connected to the gate electrode through the first contact hole; a semiconductor formed the gate insulating layer, and including a channel of a thin film transistor; a source electrode connected to the data line through the second contact hole; a drain electrode opposite to the source electrode with respect to the channel on the semiconductor; a passivation layer having a third contact hole exposing the drain electrode; and a pixel electrode connected to the drain electrode through the third contact hole are included.