A voltage generator of a nonvolatile memory device includes a pump circuit for generating a pump output voltage by performing a pumping operation and raise or maintain the output voltage in response to a double enable signal or a single enable signal, a first regulator for comparing a first division voltage with a first reference voltage and generating the double enable signal according to a result of the comparison, a second regulator for comparing a second division voltage with a second reference voltage and outputting the voltage of the first level as a first regulation voltage, and a third regulator for comparing the second division voltage with the second reference voltage and generating the single enable signal according to a result of the comparison.