A diving regulator is a pressure regulator used in a scuba set that supplies the diver with breathing gas at ambient pressure from one or more diving cylinders. The gas may be air or one of a variety of specially blended breathing gases. A gas pressure regulator has one or more valves in series, which let the gas out of a gas cylinder in a controlled way, lowering air pressure at each stage.

The terms "regulator" and "demand valve" are often used interchangeably, but a demand valve is the part of a regulator that delivers gas to the diver's mouth in a regulator with more than one stage.