To provide a pressure sensor by which a measurement error is reduced by restraining generation of stress when a temperature changes.

A cylindrical metallic pressure introducing cylinder 14 is provided, and a sensor chip 10 on which a semiconductor resistance is formed is installed on an upper end surface 20 of this pressure introducing cylinder 14. A fixing projecting part 22 or recessed part 23 is arranged on a side surface slightly lower than an upper end surface 20 of the pressure introducing cylinder 14, and this projecting part or recessed part 23 is fitted and fixed to a sensor case 12 made of a synthetic resin. A side surface of the pressure introducing cylinder 14 up to the sensor chip 10 from the projecting part 22 or recessed part 23 seprates from the resin of the sensor case 12, and forms a groove 24.