A regulator may comprise: an ADC unit for detecting a change in an output voltage and outputting an error code based on the detected result; a digital processing unit for generating a proportional control signal, a plurality of integral control signals, a counting signal, and an error sign signal based on the error code, outputting pull-up and pull-down control signals by multiplying the error code by a proportional gain factor in response to the proportional control signal, and outputting a plurality of sub-pull-up control signals by performing integration on the integral control signals based on the counting signal and multiplying the integration result by an integral gain factor; a first driving unit for outputting a first current in response to the pull-up and pull-down control signals; and a second driving unit for outputting a second current in response to the sub-pull-up control signals.