Abstract: Manhole sealing device to prevent water from entering a manhole through the corbel joint between the manhole casing and cover frame. The device comprises a flexible tube like membrane spanning the corbel joint of the manhole and provided with first sealing means above the corbel joint to seal the membrane against the inside wall of the cover frame and second sealing means below the corbel joint to seal the flexible membrane against the inside wall of the manhole casing. The portion of the membrane between the first and second sealing means is preferably provided with enough slack to form a inward fold defining an annular pocket to contain any water or other fluids entering the manhole through the corbel joint thereof. In a preferred mode of the present invention the membrane is a bag with a closed bottom to catch any water entering the manhole through or around the manhole cover. The manhole sealing device can be installed in an existing manhole without replacing any of the structural parts thereof.