A pull-up driving part maintains a signal of a first node at a high level by receiving a turn-on voltage in response to one of a previous stage or a vertical start signal. A pull-up part outputs a clock signal through an output terminal in response to the signal of the first node. A first holding part maintains a signal of a second node at a high level or a low level when the signal of the first node is respectively low or high. A second holding part maintains the signal of the first node and a signal of the output terminal at a ground voltage in response to the signal of the second node or a delayed and inverted clock signal.