PRESSURE SENSOR

PURPOSE:To provide a low-cost pressure sensor having, simplified structure in which the diaphragm operation is stabilized while avoiding an undesirable residue in the passage. CONSTITUTION:A sensor holding body 21 is provided with a flat surface 25 within a passage 22 and a hole 23 for sensor that is formed from the outer surface of the body 21 through the surface 25. Furthermore, a diaphragm 24 having an uniform thickness is provided on the same surface as the surface 25, and a pressure sensor 31 is fitted to the hole 23. Therefore, since the passage 22 has no harmful recess therein to leave a fluid, the purity and cleanliness of the fluid is hardly decreased when the pressure sensor is to be used while it is connected with a piping system for fluid necessary for purging. Further, a fluid passing through the passage 2 shows a smooth fluidity. In addition, since the diaphragm 24 and body 21 are formed together as one body, no assembling and sealing processes for the diaphragm 24 are needed.