Magnetic fluid sealing device and magnetic fluid sealed bearing

摘要

One object is to provide a magnetic fluid sealing device in which a magnetic fluid retained between a polar plate and a drive portion can be effectively prevented from spilling, so as to retain waterproofness for a long period. A magnetic fluid sealing device of the present invention includes a ring-shaped polar plate encircling a drive portion and retaining a magnet; and a magnetic fluid retained in a gap between the drive portion and the polar plate by a magnetic force of the magnet. The polar plate has a spill preventing portion provided thereon, the spill preventing portion having a projecting wall that is disposed distant from an end surface of the polar plate retaining the magnetic fluid, so as to prevent spill of the magnetic fluid.