A pressure sensor module 2, wherein a holding space 34 is formed between a diaphragm 22 and a thin film layer 31, and a vent hole 321 communicating with the exterior of a first case is provided in the holding space 34. In the above pressure sensor module, even when a corrosive gas or chemical solution is used as a fluid to be measured and a corrosive gas component originated from the fluid to be measured permeates into the holding space 34, the permeated corrosive gas component can be discharged to the outside of the case through the vent hole 321. As a result, the corrosion of the diaphragm 22 by the fluid to be measured can be prevented, which results in the achievement of a prolonged service life of the pressure sensor module 2.