Abstract: A high voltage generator comprising a charge pumping circuit including a precharge circuit for generating a high voltage and a plurality of transfer transistors connected to the precharge circuit for transferring the high voltage. The charge pumping circuit further includes a voltage controller for varying the voltage to a well including the transfer transistors according to a relative variation between an external supply voltage and the high voltage. P-N junctions formed in the well can be prevented from being forwardly biased, so that a latch-up phenomenon cannot occur. Further, because the charge pumping operation is not influenced by the level of the high voltage, the charge pumping circuit can be prevented from being erroneously operated due to an instable transient characteristic, even in the case where the initial external supply voltage has a low value.