To provide a diaphragm type pressure sensor having superior durability and improved to respond to a pressure change of a pressure chamber with good sensitivity and correctly detect a pressure linearly.

A sense object 21 is set to a diaphragm 7, and a detecting element 23 which senses the sense object 21 and generates an electric signal corresponding to a distance to the sense object 21 is mounted at a casing 5. A change of the distance between the sense object 21 and detecting element 23 corresponding to a shift of the diaphragm 7 because of a pressure introduced to pressure chambers 13, 15 is detected by the detecting element 23. The pressure is detected from the electric signal output from the detecting element 23 in a diaphragm type pressure sensor. The diaphragm 7 is formed of a diaphragm main body 9 of a resin thin film having a larger outer diameter than an inner diameter of the casing 5 and a metallic retainer plate 11 set at a central part of the diaphragm main body 9.