PURPOSE: To facilitate the manufacture by forming a valve member into a truncated sphere, and holding the valve member in a hollow chamber of a fitting member through a coil spring in a fuel pressure regulator valve to open/ close the valve member through a diaphragm unit according to the pressure of a regulation chamber to be connected to a vacuum regulation device.

CONSTITUTION: A cylindrical casing 12 is divided into a regulation chamber 16 and a fuel chamber 18 by a diaphragm unit 14, the fuel chamber 18 is connected to a fuel rail and to a fuel tank through an inflow part 20, and an outflow part 22, respectively, and the regulation chamber 16 is connected to a vacuum regulation device through a regulation hole 44. The unit 14 is provided with a metallic annular member 26, and its inner edge part is held between a metallic fitting member 28 and an annular member 30. A truncated sphere 32 is fitted to a hollow chamber 34 of the fitting member 28, and held by a washer 36, and energized to the washer 36 side by a coil spring 38. The unit 14 is energized to the fuel chamber 18 side by a spring coil 40, and the truncated sphere 32 is pressed against a valve seat 24 thereby.