Abstract: A pressure sensor adapted for use in pressure switches, pressure detectors, pressure measuring instruments, etc. has a housing. The housing has at one end a force balance valve including a gas chamber sealed at one end by a valve diaphragm and filled with a pressurized gas, and at the other end a pressure receiving section sealed at one end by a pressure receiving diaphragm. The housing further has first and second cylinders with corresponding first and second pistons held in contact with the valve diaphragm and the pressure receiving diaphragm, respectively. Between the first and second pistons is provided a connecting member with an actuating section. The housing further has a working section which is actuated by the actuating section to provide an output or signal externally.