ELECTRONICALLY CONTROLLED REGULATOR

Provided is an electronically controlled regulator (1A) having a body (10A) sectioned into a high-pressure chamber (2A), a discharge pressure chamber (3A), a pressure control chamber (4A), and an atmospheric pressure chamber (5A), and including a pressure regulating valve including: a valve shaft (21A) having a valve body (22), a valve seat (23) in close contact with the valve body (22), and a discharge pressure regulating unit that regulates a fluid pressure by causing the valve shaft (21A) to reciprocate through driving of an electric motor (30), in which a high-pressure fluid introduced is regulated to a set pressure and discharged, and three diameters of a seat diameter (Ds) of the valve seat (23) as a boundary between the high-pressure chamber (2A) and the discharge pressure chamber (3A), a seal diameter (Dh) of an O-ring (72) which is a seal member on the atmospheric pressure chamber side as a boundary between the high-pressure chamber (2A) and the atmospheric pressure chamber (5A), and a seal diameter (Do) of the O-ring (71) which is a seal member on the pressure control chamber side as a boundary between the discharge pressure chamber (3A) and the pressure control chamber (4A), are made substantially the same.