A thin film transistor array panel includes an insulation substrate; a gate line and a first electrode on the insulation substrate; a gate insulating layer on the gate line and the first electrode; a data line on the gate insulating layer; a passivation layer on the gate insulating layer and the data line; and a second electrode on the passivation layer. Relative permittivity (ε) of the gate insulating layer is more than about 15, and a thickness of the gate insulating layer is about 2000 angstroms.