A reference voltage generator for improving setup voltage characteristics without an increase in a standby current and a method of controlling the same, in which the reference voltage generator includes: a reference voltage generation unit including a resistor connected between a power supply voltage and an output node, for dividing the power voltage, and generating a reference voltage fed to the output node thereof; a voltage detector receiving a feedback of the reference voltage and detecting a level of the reference voltage; and a bypass circuit connected in parallel to the resistor of the reference voltage generation unit and bypassing the resistor in response to an output signal of the voltage detector.