PURPOSE: To prevent trouble in a block even it ambient temperature is changed, by connecting that part of the outer wall of a dither mechanism whose rigidity is lowest to the circular opening of the block.

CONSTITUTION: This gyroscope is composed of reflecting mirrors 14, which are attached to the vertexes of a polygonal, generally triangular, block 12, a prism 16, photodetector 18 and the like. A dither mechanism is mounted in order to apply fine vibration on said block 12. The dither mechanism is composed of a cylindrical outer wall part 26 and a plurality of arms 28, which are extended in the radial direction in the inside and support the outer wall 26. Piezoelectric elements are bonded to both sides of the arms 28. Usually, a circular opening corresponding to the part of the dither mechanism is provided at the central part of the block 12 for the dither mechanism having the circular outer wall 26. The dither mechanism is coupled into the opening and bonded as required.