To provide a pressure regulator having a butterfly valve, capable of regulating a valve downstream pressure with higher accuracy.

This pressure regulator 1 has the butterfly valve 3 disposed inside an intake conduit 2 and a drive part 4 opening/closing the butterfly valve 3, and nearly constantly regulates the downstream pressure of the butterfly valve 3 with an upstream pressure of the butterfly valve 3 as drive force. The pressure regulator 1 has a downstream feedback pressure correction mechanism 6 detecting a differential pressure between a static pressure and the whole pressure downstream of the butterfly valve 3, correcting the downstream pressure on the basis of the detected differential pressure, and supplying it to the drive part 4. Accordingly, fluctuation of the pressure changed by a flow rate change downstream of the butterfly valve 3 is suppressed to improve the pressure regulation accuracy.