PURPOSE: A liquid crystal display device and a driving method thereof are provided to remove the need of an additional mask for doping by using a voltage of a front or rear gate line. CONSTITUTION: A driving method of a liquid crystal display device comprises the steps of: stepping up a first input voltage(Vin1) in multiple stages to generate a gate-on signal(VGH) and stepping down a second input voltage(Vin2) to generate a gate-off signal(VGL). In the gate-on voltage generating step, the first input voltage is boosted to first to third boosted voltages(VGH1-VGH3) sequentially.
