Abstract: This invention discloses an emergency shaft seal device wherein a packing ring of elastic material the inside diameter of which is larger than the outside diameter of a rotatable shaft is received in an annular groove along the periphery of the rotatable shaft to be free and not in contact with the rotatable shaft, and in the event of abnormal condition of a main shaft seal device used under the normal conditions, the packing ring is deformed by the pressure of a pressurized fluid applied to the outer periphery of the packing ring to be equally pressed to the periphery of the rotatable shaft so that the sealing is performed by the packing ring in place of main shaft seal.