Abstract: A shaft sealing device comprises a rotation shaft passing through a casing. A rotation ring mechanism is affixed to the rotation shaft within the casing, with a mechanical seal member located within the casing, with a mechanical seal member located within the casing and cooperating with one side of the rotation ring mechansim. A non-rotatable, floating seal member is also located in the casing, and is liquid-tightly fitted onto the outer circumference of the rotation ring mechanism. One side of the floating seal member contacts an inner surface of the casing, so that a sealing chamber for lubrication liquid is formed within the casing, by the rotation ring mechanism, mechanical and floating seal members.