PURPOSE: To improve vibration resistance and maintenance property with a compact configuration by providing a pressure-reception part, a signal processing part, and a display part on nearly the same axis and changing the relative positions of each part.

CONSTITUTION: A pressure-reception part 120, a signal processing part 190, and a display part (matrix LCD) 140 are provided on nearly the same axis for achieving a sufficient resistance against vibration and at the same time a compact device with an improved assembly property can be obtained. Also, by changing the relative position combination between the pressure-reception part 120 and the processing part 190, the display direction of wire and the position of the lead switch 1121 can be changed in 90° pitch for improving the maintenance property while the pressure-reception part 120 is mounted to a pressure-guiding pipe 102. Then, zero point is adjusted by operating a magnet to the non-mechanical switch 1121 utilizing the principles of an electromagnetic relay, thus easily achieving an adjustment without any erroneous operation and at the same time securing reliability for airtightness without requiring a through hole at the processing part 190.