The invention relates to an actuator comprising a leaf spring attached to a carrier in at least one point of attachment, means for providing a magnetic field and means for guiding the magnetic field so as to provide a magnetic flux loop. A movable part of the leaf spring is movable relative to the means for providing the magnetic field. The actuator further comprises a drive core attached to the movable part of the leaf spring, which is incorporated in the flux loop, for imparting the relative movement to the movable part. The drive core is so positioned that the magnetic properties of the flux loop are changed under the influence of said relative movement for gearing the magnetic force on the drive core and the spring force of the leaf spring to each other.