PURPOSE: To provide the micro pressure fluctuation detection unit which is high in pressure detection sensitivity, excellent in corrosion resistance, less degraded in characteristics, and easy to manufacture.

CONSTITUTION: A flexible insulating thin film 2 is stretched over the upper surface of a substrate stationary ring 1, and a lower electrode 3 and a piezo electric element 4 are provided over the film. A first stationary ring 5 having a first cut-out section at its section corresponding to the electrode outlet section 3a of the lower electrode 3 is provided so that the lower electrode 3 and the piezo electric element 4 are thereby enclosed. An upper electrode 7 is set up over the piezo electric element 4, and a passivation film 8 is provided over the upper electrode for its protection. A second stationary ring 9 is provided to enclose the circumference of the first stationary ring 5. The insulating thin film 2, the passivation film and the stationary rings 1, 5 and 7 are made out of a fluorine resin system high polymer compound excellent in corrosion resistance against city gas. The fluorine resin system high polymer compound is treated by high voltage corona discharge in such a way that its surface is activated so as to be capable of being bonded with adhesives.