PURPOSE: To obtain a highly-precise measured value under no influence of variation in ambient temperature by providing a measuring diaphragm and wave-shaped diaphragm is an external cylinder with a bottom, and then by filling it with an insulating solution.

CONSTITUTION: External cylinder 23 with bottom 22, equipped with diaphragm pedestal 26, pressure measuring diaphragm 27, insulator 32, reference electrode plate 37, plate spring 38, cradle plate 42, and wave-shaped diaphragm 43 is filled with an insulating solution and hermetically sealed. Insulator is provided with electrodes 29A and 29B of metal foil and electrodes, diaphragm 27 and reference electrode plate 37 are held at fixed intervals. Pressure to be measured, when applied to wave-shaped diaphragm 43, operates on pressure measuring diaphragm 27 through a through hole and insulating oil to change a capacitor value between it and electrode 29A, so that the pressure can be measured. Through the operation of wave shaped diaphragm 43, a measured-value error is never caused by variation in temperature.