To provide a sealing device of a valve stem capable of certainly sealing a shaft insertion portion of the valve stem without compressing it by a rotation and an urging force and provided with a maintenance seal having a long seal life without requiring a re-adjustment after replacement of a seal packing.

In the sealing device of shaft such as a valve stem 3, a packing accommodation part 9 is provided at the outside of a shaft insertion part 7 of a casing 2, a seal packing 10 is retained in a packing case 11 accommodated in the accommodation part 9; a maintenance seal 13 is accommodated at the shaft insertion part side of the packing 10 of the accommodation part 9; and a pressurizing means for sealing the shaft insertion part 7 by elastically deforming the seal 13 at the time of repairing the packing 10 is provided. The seal 13 comprises a retaining ring 22; and an elastic body 21 attached so as to form a sealing space 23 at an inner surface side. The pressurizing means feeds a pressurized fluid to the sealing space 23 and expands the elastic body 21 to seal it.