A piezoelectric/electrostrictive membrane type sensor is provided with a ceramic base body and a piezoelectric/electrostrictive element. The ceramic base body includes a thin diaphragm portion, a thick portion and a cavity formed by the portions. The piezoelectric/electrostrictive element is arranged on the ceramic base body and also includes a piezoelectric/electrostrictive body, and an upper electrode and a lower electrode sandwiching the piezoelectric/electrostrictive body. Further, the piezoelectric/electrostrictive body contains an alkaline metal or an alkaline earth metal, with the upper electrode and the lower electrode containing gold or platinum. When there is a change in the atmosphere at a place where the sensor is used, the sensor copes with such change and at least prevents the continuation of a low-quality measurement.