PURPOSE: To detect force with high accuracy, regardless of unwanted vibration from the outside.

CONSTITUTION: A vibrating part 1 vibrated by applying voltage to electrodes 1a, 1b is composed of a piezoelectric element. The piezoelectric element is brought into direct or indirect contact with a measured object, and force is detected while vibrating the piezoelectric element. Because of detecting force while vibrating, force can be detected with high accuracy even if there is unwanted vibration from the outside.