PURPOSE: To measure pressure accurately by providing a measurement plate, a static pressure sensor, a differential pressure sensor, a high-pressure separator, a low-pressure separator, a low-pressure diaphragm, first and second fluid rooms, and a measurement diaphragm and supplying high and low pressures to the outside of the high-pressure and low-pressure diaphragms.

CONSTITUTION: A low-pressure separator 10, a high-pressure separator 12, and a measurement plate 14 are used, a high-pressure separation diaphragm 16 is mounted to the high-pressure side of the plate 12, and a low-pressure separation diaphragm 26 is mounted to the opposite side of the plate 10. A measurement diaphragm 18 is mounted to the high-pressure side part of a conduit 30 that is extended between series conduits 32 that run from a low-pressure diaphragm room 28 to the bottom of a differential pressure sensor 34 and a static pressure sensor 36. A room 24 at a high-pressure side passes through a series conduit 38 and is connected to the high-pressure side part of the measurement diaphragm 18 and the high-pressure side part of the sensors 34 and 36. Then, high and low pressures are supplied to the outside of high-pressure and low- pressure diaphragms, thus measuring low differential pressure and static pressure accurately.