PURPOSE: To press in a driven ring easily without damage for a shaft sealer on compressor side of a supercharger by locating a sealed end face formed by contacting surfaces between a seating ring and a driven ring on more inner side than location of an edge of a shrouding ring which covers the driven ring.

CONSTITUTION: First, place the seating ring 13 on the shoulder 23 of the shaft 14 which is permanently joined to the turbine wheel of the supercharger, and then put a collar 24 and an impeller 25 of the compressor on the shaft in direct contact with each other, and those are secured with machine screws. The driven ring 12 is placed so as to form the sealed end face against the contacting surface of the seating ring 13. The driven ring 12 is placed inside the shrouding ring 16 and forced against the sealed end face 11 mentioned above to maintain required pressure against it for sealing with a spring 20 and a seal ring 38 contained in the shrouding ring. For such a shaft sealing device, the sealed end face 11 between both rings 12, 13 are to be located on more inner side than location of the edge bent inward 44 on open side of the shrouding ring 16, so that the driven ring 12 can be pressed in easily without fear of damage.