Abstract: A pressure sensor for detecting the pressure of a medium bounded by a wall, in particular for detecting the pressure in the pump work chamber of a fuel injection pump, with a housing that is disposed in a through bore of the central screw plug of the fuel injection pump. The housing has a separate front housing part, which is welded to a measuring element support and together with this measuring element support, a measuring element, a pressure transmission element, and a membrane that constitutes the bottom of the front housing part, constitutes a measurement head that is definitely braced in the pressure transmission direction and cannot be disassembled. The measurement head contacts the through bore and other components of the pressure sensor exclusively by way of an outer flange, which is disposed on the outer circumference of the measurement head.