Pressure detection device and pressure sensor

A pressure detection device comprising:

• a flow passage unit in which a flow passage for introducing a fluid is formed;
• a pressure detection unit configured to detect a pressure of the fluid;
• and
• a mounting mechanism by which the flow passage unit is detachably mounted on the pressure detection unit, wherein
• the flow passage unit includes:
• a pressure receiving diaphragm configured to be displaced upon receiving the pressure of the fluid flowing through the flow passage on a first surface of the pressure receiving diaphragm;
• and
• a first connection portion attached to a second surface of the pressure receiving diaphragm,
• the pressure detection unit includes:
• a pressure detecting diaphragm having a first surface to which a pressure is to be transmitted from the first connection portion;
• a second connection portion attached to a center portion of a second surface of the pressure detecting diaphragm;
• and
• four strain resistance portions attached to the second surface of the pressure detecting diaphragm, the strain resistance portions being connected to each other so as to form a Wheatstone bridge circuit,
• one of either the first connection portion or the second connection portion is formed of a magnet, and the other of either the first connection portion or the second connection portion is formed of a magnet or a magnetic body,
• the first connection portion and the second connection portion are arranged such that the first connection portion and the second connection portion are attracted by a magnetic force in a state where the flow passage unit is mounted on the pressure detection unit by the mounting mechanism, and
• the four strain resistance portions are attached to a region of the second surface of the pressure detecting diaphragm other than the center portion.