PURPOSE: To reduce the manhour and to improve the quality for the circuits of electrodes, etc., which are formed on both sides of a light transmissive substrate of quartz, etc.

CONSTITUTION: When the electrodes are formed on both sides of a vibrating gyro made of a quartz crystal substrate, a chromium thin film 102 and a gold thin film 104 are formed by vapor deposition on both sides of each vibrating piece. Then both sides of the vibrating pieces are irradiated by the YAG laser beams through the upper surface side of the vibrating gyro after the beams are focused by a lens. At the same time, the laser focal point (f) is set at the middle points of both sides of both vibrating pieces 86 and 92 respectively. Therefore both films 102 and 104 are fused and evaporated only at the part irradiated by the YAG laser beam on the upper surface side of each vibrating piece and at the beam incident side. Furthermore both films 102 and 104 are also fused and evaporated only at the part where the laser beam is emitted on the lower surface side of each vibrating pieces and at the beam emitting side.