To detect the abnormality of a diaphragm itself in a pressure sensor for outputting an electric signal on the basis of the distortion of the diaphragm deformable by pressure application.

This pressure sensor 100 comprises a piezoelectric element 3 as a distortion imparting member for forcedly distorting the diaphragm la. A voltage is applied to the piezoelectric element 3 to distort the diaphragm 1a, whereby the output from a strain gauge 1b is diagnosed.