To stand a large current when a load is particularly large and reduce the loss in power consumption when the load is normally small in a charge pump and booster circuit using capacitors alternately charged and discharged.

A pre-booster circuit 4 and a post-booster circuit 6 sequentially boost a power supply voltage VCC and output voltages VEM, VOUT. An output voltage monitor circuit 8 monitors the voltage VEM. If the voltage VEM decreases, an instructing signal (up) for enhancing a boosting capability is outputted. If the voltage VEM unnecessarily increases, an instructing signal (down) for reducing the boosting capability is outputted. A boosting clock forming circuit 2 sets frequencies of boosting clock signals A, B in response to the instructing signals. Since the booster circuits 4, 6 operate with capabilities corresponding to the loads, the loss in power consumption is reduced when the load is normally small.