PURPOSE: To relieve or eliminate high-order resonance by fitting a damping member to an objective lens holder via an adhesive member having viscosity so that a mounting face is made in parallel with a vibration resonance direction by the driving control of the objective lens.

CONSTITUTION: When a balancer 4-1 is fitted to a lens holder 3, the holder is fitted via an acrylic system both-side adhesive tape 7 as an adhesive member as to only a face in parallel with a face perpendicular to the lens holder, that is, the vibration resonance direction by the damping drive of the objective lens 2. The balancer 4-1 is folded in an L shape and the degree of freedom of the balancer 4-1 in the vertical direction via the both-face adhesive tape 7 is ensured while the air gap 8 retains except the vertical adhesive face. The objective lens 2 is adhered to the lens holder 3. The lens holder 3 is moved turnably and vertically freely by using a slide hole 9 as a guide. The balancer 4-1 is provided on the side opposite to the objective lens to take the weight balance in the case of tracking control by the rotation and of focusing control by the vertical movement.