A reference voltage generator according to an embodiment of the present invention includes: a voltage setting circuit generating a first voltage having a predetermined voltage difference from an output voltage; a voltage buffer receiving the first voltage and outputting a first power supply substantially equal to the first voltage; a voltage clamp circuit operating based on a second power supply and a third power supply; and a band-gap circuit generating the output voltage, the band-gap circuit operating based on the second power supply and the first power supply output from the voltage clamp circuit.