An active matrix display device includes: a display panel having gate lines and data lines defining pixels; a gate driver in the display panel to supply output signals to gate lines of the display panel; and a data driver to supply image signals to data lines of the display panel, wherein the gate driver includes a plurality of shift registers to output signals that are sequentially shifted, eachof the shift registers including: a first control part for controlling a first node in response to a first clock signal among a plurality of clock signals; a second control part for controlling second and third nodes in response to the start signal and a second clock signal; and an output part to selectively output one of a third clock signal and a first supply voltage in response to voltages of the first, second, and third nodes, whereby second and third supply voltages, which are different from each other, are switched for application at the second and third nodes.