PURPOSE: To increase the amplitude of shear vibration of a vibrator by arranging a buckling spring perpendicularly to parallel faces and changing the distance of the faces by piezoelectric vibration so as to generate the shear vibration in parallel to the faces.

CONSTITUTION: A ladder form coupler 5 where buckling springs formed by bending a steel plate into a semicylindrical shape having a prescribed radius of curvature are arranged at an equal interval is inserted between terminal boards made of a center plate and a steel plate of the same shape. The piezoelectric vibrators 1 and 2 overlapped thereupon and steel-made trapezoidal vibrators 3 and 4 are overlapped from the outside and bolted from both sides. In increasing the tightening force, the buckling springs are buckled and the center plate is kept in the form of shear deformation so as to constitute the piezoelectric vibrator of the shear mode.