PURPOSE: To make focus adjustments with high accuracy by supporting a base which is guided in directions of an optical axis by a couple of guide members for focus adjustments by the guide members at three points and pressing it against one guide member by an energizing member.

CONSTITUTION: When a motor 18 for focus adjustment is driven after a slider 15 is moved in the direction of the optical axis for optical variable power a guide (driving) shaft 21 rotates to move forth and back the base 27 through support parts 27a and 27b in the direction of the optical axis, and the distance of a solid-state image pickup element 10 to a reduction optical system 9 is varied to make a focus adjustment. At this time, the base 27 is supported on the guide (driving) shaft 21 at two points and on a guide shaft 22 at one point, i.e. three points in total, so there is no play. The base while pressed axially by a coil spring 34 is pressed radially by coil springs 33 and 33, so a back-lash occurs to neither female screws of the support parts 27a and 27b nor the external screw of the guide (driving) shaft 21.