Each Lens support member 22, 23, holds a lens capable of being driven for displacement in unison with the lens for desired optical adjustment. A guide bar 26 restricts the lens support member such that the displaceable direction thereof is along a predetermined direction. An actuator element includes a curved plate-like electrostriction element of a polymer material layer laminate disposed curvedly along and in a state of being wound on part of an outer periphery of the guide bar for generating a drive displacement such as to be expanded or compressed in the longitudinal direction of the guide bar when a drive voltage is applied across the element, the drive displacement being capable of being transferred to the lens support member.