A lens holder is so supported that the lens holder is movable along a
supporting shaft in parallel to an optical axis of the object lens, and
rotatable about the supporting shaft. Magnets are mounted on the lens
holder. Focusing coils and tracking coils having sides facing the magnets
are mounted on a base on which the supporting shaft is planted. Yokes are
so provided that the yokes and the magnets respectively sandwich the
focusing coils and the tracking coils. The yokes have facing portions
that face respective magnetic poles of the magnets and extending portions
extending in the directions away from the magnets.