PURPOSE: To prevent the hysteresis of a diaphragm from becoming larger due to stresses concentrated to the fulcrum section of the diaphragm.

CONSTITUTION: Ceramic films 31 and 32 are respectively formed on both surfaces of the fulcrum section D of a diaphragm 30. An internal compressive stress is generated at room temperature in the film 31 formed on the side face of the section D on the side of fluid to be measured and the film 31 exerts a force to the diaphragm 30 in the direction in which the diaphragm 30 is extended, because the film 31 is formed at 300-400°C, and an internal tensile stress is generated at room temperature in the film 32 formed on the side face of the section D on an enclosed liquid side and exerts a force to the diaphragm 30 in the direction in which the diaphragm 30 is contracted, because the film is formed at ≥700°C.