To provide a transducer having a pressure-sensitive member producing an electric signal quickly in response to the pressure of combustion chamber.

A transducer housing to be fixed to a port in a combustion chamber is provided with a metal diaphragm 34 exposed to combustion gas. Pressure of combustion gas causes displacement of the diaphragm 34 which causes local displacement of a beam member 44 supported simply. The beam 44 has one side made of a heat-resistant material on which a piezoelectric resistor element is formed through epitaxial growth and connected with a bridge circuit. Noble metal foil lead wires 50, 52 are connected with the piezoelectric resistor element forming a bridge and provided with fixing pads. The pad is welded to other noble metal toil pad formed on a ceramic substrate 42 to form a sensor assembly 40 which is fixed closely to the diaphragm 34 thus constituting a transducer.