PURPOSE: To detect a very low pressure with high accuracy for a long time irrespective of the ambient temperature by forming a film plate of a thin diaphragm spread in a plate-like state and piezoelectric ceramic film which is provided with electrode layers on both surfaces and is stuck to one surface of the thin diaphragm and detecting pressures from strains generated in the film plate.

CONSTITUTION: A film plate 14 is formed so as to eliminate the need of temperature correction from the title pressure sensor by sticking a piezoelectric ceramic film 20 composed of, for example, lead zirconate titanate to one surface of a thin diaphragm 19 composed of a high- conductivity metal 19 of about 100μm in thickness and forming electrode layers on both surfaces of the ceramic film 19 by sticking sliver, etc., to both surfaces by burning, and then, connecting the electrode layers to an amplifier 22 through a signal leading-out wire 23. By positioning the film plate 14 in the center of each pressure chamber 15 and 16, the vibration of the drift current of a, for example, fluidic flowmeter is led to the chambers 15 and 16 from the pressure output ports 11 and 12 of the chambers 15 and 16 through entrance nozzles 15a and 16a. Therefore, the film plate 14 vibrates due to a differential pressure and a potential difference is generated between both electrode layers of the ceramic film 20 in corresponding to a strain. The output is amplified 22 and the flow rate of the drift current is found from the number of vibrations of the current.