PURPOSE: To improve hysteresis characteristics of a nozzle flapper mechanism by forming a nozzle hole on a silicon substrate through etching, by providing first and second communicating passages in a base block, by connecting the silicon substrate and the base block so that one end of the first communicating passage faces to the nozzle hole, and by attaching a flapper made of silicon on the silicon substrate.

CONSTITUTION: A silicon substrate 11 has a nozzle hole 12 manufactured by etching and is connected to a base block 13. The base block 13 has a first communicating passage 14 and a second communicating passage 16. One end of the first communicating passage 14 leads to the nozzle hole 12 and another end forms an inlet port 15. On the other hand, one end of the second communicating passage 16 leads to the first communicating passage 14 and another end forms an output port 17. A flapper 18 made of a silicon plate is arranged so as to face to the nozzle hole 12 and is joined to the silicon substrate 11 through a glass plate 19 at one end of the flapper 18 so as to constitute a nozzle flapper mechanism. When air pressure is supplied to this nozzle flapper mechanism from the input port 15 and electric voltage is applied to the flapper 18, the back pressure discharged from the output port 17 has characteristics of weak hysteresis because the flapper 18 is made of silicon.