Provided is a pressure detection device which includes a pressure detection unit 10 and a flow passage unit 20. The pressure detection unit 10 includes a pressure sensor 12 including a diaphragm 12a and a first connection portion 11 joined to the diaphragm 12a. The flow passage unit 20 includes a diaphragm 22 and a second connection portion 23 joined to the diaphragm 22. One of the first connection portion 11 and the second connection portion 23 is formed of a magnet, and the other of the first connection portion 11 and the second connection portion 23 is formed of a magnet or a magnetic body. In a state where the flow passage unit 20 is mounted on the pressure detection unit 10, the first connection portion 11 and the second connection portion 23 are disposed in a state where the first connection portion 11 and the second connection portion 23 are attracted to each other by a magnetic force.
