PURPOSE: To capacitively specify pressure over a wide range by only using a single non-complicated converter.

CONSTITUTION: A pressure converter is separated from fluids enclosed in areas representing various fluid pressure states and has a diaphragm 9 containing a mobile conductive capacitor electrode surface and a composite capacitor device arranged in one of the areas. The capacitor device can be moved together with the diaphragm 9 in a state where a narrow interval is maintained between the device and the electrode surface of the diaphragm 9 and is composed of a flexible member which forms a first variable capacitor together with the electrode surface and a relatively rigid member that has a relatively stationary conductive electrode surface fitted to the electrode surface of the flexible member at an interval and forms a second variable capacitor. The pressure converter is constituted in such a way that the composite diaphragm device is positioned to the diaphragm 9 and the diaphragm 9 deforms the flexible member by the pressure difference between areas exceeding a prescribed range in response to the pressure difference. Therefore, pressure can be specified over a wide range.