PURPOSE: To enable the preventing of the destruction of a sensor by providing a pressure receiving chamber with a deformation member for changing the volume of the inside of the pressure receiving chamber by a differential power or a pressure to suppress a rise in pressure within the pressure receiving chamber.

CONSTITUTION: A spherical recess part 36 is formed at the central part of a recess part 35 communicating with a pressure introduction port 32 and a ball body 37 is housed therein functioning as deformation member that is made of a material at a large volumetric compression rate such as teflon or rubber and is deformable by a pressure exceeding a specified value. A measured pressure applied into a lead pipe is transmitted to the recess part 35 through the introduction port 32 and applied to a sensor 21 through a liquid sealed into a diaphragm 25. At this point, even when the ball body 37 is deformed, the supply of the pressure from the lead pipe prevents measuring errors. On the other hand, when a temperature rise occurs in a closed space with the closing of a valve in the course of the lead pipe, a fluid inside expands to raise the pressure. But the volume of the ball body 37 reduces and suppresses a pressure rise within the pressure receiving chamber by absorbing the volume increased thereby allowing the preventing of an excessive pressure from being applied to the sensor 21.