An actuator for an optical pickup having a base on which a holder is fixed, a
bobbin, a support member, and a magnetic circuit. A plurality of installation holes
are formed in the bobbin such that a plurality of objective lenses to record and/or
reproduce optical discs having different recording densities are installed at different
heights. The support member has one end coupled to the bobbin and the other end
coupled to the holder movably supports the bobbin. The magnetic circuit drives
the bobbin in focusing and tracking directions. The magnetic circuit is divided
into a first magnetic circuit to drive the objective lenses in the focusing direction,
and a second magnetic circuit to drive the objective lenses in the tracking direction,
thereby reducing the weight of a moving portion.
