The present invention discloses an internal
voltage generator which can
restrict abnormal variations of an internal
voltage resulting from a leakage current generated in a driving
transistor. The internal
voltage generator includes a
comparator for receiving a reference voltage through its first input terminal, receiving the internal voltage through its second input terminal, and comparing the reference voltage with the internal voltage, a driving
transistor for receiving the output
signal from the
comparator through its gate terminal, a first terminal of which being coupled to a driving voltage, a second terminal of which being an output terminal for outputting the internal voltage, a
back bias circuit for supplying a predetermined potential of
back bias voltage to a well region of the driving
transistor, and a controller for receiving the output
signal from the
comparator, and controlling the operation of the
back bias circuit. The second terminal of the driving transistor is feedback-coupled to the second input terminal of the comparator. When the driving transistor is turned off according to the output
signal from the comparator, the controller for receiving the output signal from the comparator supplies the predetermined potential of back bias voltage to the well region of the driving transistor by driving the back bias circuit.