A voice coil motor for a disk drive includes a permanent magnet, a voice coil adapted to move in an arc proximate to the permanent magnet, a top plate positioned above the voice coil, and a bottom plate positioned below the voice coil. The permanent magnet has two halves that are magnetized in opposite direction. The two halves of the magnet are split into a right half magnet portion and a left half magnet portion. The right half magnet portion and the left half magnet portion are attached to the top plate and the bottom plate respectively at opposite sides of the voice coil motor. The invention also discloses a disk drive unit with such VCM.