A first charge pumping circuit including a first capacitor and first and second switches, and a second charge pumping circuit including a second capacitor and third and fourth switches, are operated complementarily. The first capacitor is provided between first and second nodes, and the second capacitor is provided between third and fourth nodes. An NMOS transistor as equalizing means is provided between the first and third nodes. Before the start of supply of charges by the second switch to the second node and injection of charges by the third switch to an output node, the NMOS transistor is turned on, whereby potentials at the first and third nodes are equalized. Accordingly, the charges consumed by the first charge pumping circuit can be recycled by the second charge pumping circuit. Thus, lower power consumption is realized.