A pressure regulator can be used particularly in a CNG-operated motor vehicle as an electronically controlled pressure reducer for maintaining the gas pressure constant on the injection valve used for filling the respective cylinder. The pressure regulator is composed of a control unit (1), a pressure reducer (3) that is controlled by the control unit (1), and a throttle (2) which connects the gas outlets (20, 40) of the working chamber (17) of the control unit (1) and the pressure reducer (3). A piezoelectric actuator (11) which affects the valve (21, 22) of an overflow device (14) makes it possible to specifically modify the gas pressure (P2) in the working chamber (17) of the control unit (1) and simultaneously influence the position of the valve (38, 39) of the overflow device (33) of the pressure reducer (3), thus allowing the output pressure (Pout) of the pressure reducer (3) to be adjusted to a predefined desired value.