To realize a vacuum gage robust against disturbance and capable of detecting precisely a degree of vacuum.

A vibration body 1, a beam 2 and a housing 3 cut out of one sheet are fixed onto a base panel 6 via a spacer 5. The vibration body 1 has an asymmetric outer shape with respect to a Y-axis passing through the gravity center 4, and generates inertia rotation vibration around the beam 2 of an elastic body, in accompaniment to translational vibration of the vibration body 1, when exciting force is applied in the gravity center position of the vibration body 1 by an excitation electrode 7 on the base panel 6. A speed increase in an amplitude (rotation angle) of the inertia rotation vibration is detected since the inertia rotation vibration is increased by force received from an atmosphere, and a detected value is compared with a reference data to find atmospheric pressure.