A voltage regulator uses a comparing apparatus having hysteresis characteristics. The voltage regulator includes a comparator for comparing a comparison voltage with a reference voltage, and outputs a result of the comparison; a switching controller for generating a plurality of switching signals in response to the comparison result; resistors connected in the form of a string, to divide the comparison voltage into a plurality of voltages; and a switching box for selecting one of the plural voltages, as the comparison voltage, in response to the switching signals.