A charge pump circuit may include a plurality of charge pump cells. Each charge pump cell may further include an output node for supplying charge, a pumping node for receiving a clock signal and a pumping capacitor, which may be connected between the output node and the pumping node, for storing the charge and may repeat a charge or discharge operation and/or a pre-charge operation in response to a plurality of clock signals. In the pre-charge operation, a unidirectional charge supply may be performed from a lower voltage output node to a higher voltage output node.