PURPOSE: To obtain a vacuum sensor having a small size, strength to impact and excellent reliability by using a lithium niobate which is produced by selecting the cutting angle of the resonator to provided min. power sensitivity regardless of the shape of the resonator.

CONSTITUTION: The torsional mode lithium niobate resonator 1 is supported and fixed at both ends thereby an adhesive agent 4, etc. onto a supporting pedestal 2. The pedestal 2 is made of an insulating material such as ceramics. The resonator is thus made strong to disturbance, more particularly to heavy impact force unlike a cantilever type. The cutting angle of the resonator 1 is selected in the angle range rotating a Y plate by 100W130° around the X-axis as the axis of rotation, by which the min. power sensitivity is obtd. regardless of the shape of the resonator. More specifically, the tensile force or compressive force to the resonator generated by a temp. change is minimized by selecting the cutting angle of the resonator 1.