PURPOSE: To prevent leakage of oil in a supercharger by rotatably providing a collar on a driving shaft in the vicinity of a compressor wheel in the supercharger integratedly with the driving shaft, and arranging a retainer on the outer circumferential side of the collar through a seal ring.

CONSTITUTION: In a collar 11, a retainer 12, and a deflector 13 as a mechanism for preventing oil from leaking to a compressor wheel side in a turbo charger 1, a groove 17 is formed o the collar 11, a seal ring 18 is mounted, and slinger 19 is provided on the outer circumference of the collar 11. A rib 21 is provided adjacently to the slinger 19, the first surface 22 of the inside of the rib 21 and the second surface 23 of a penetrating hole 14 side in the deflector 13 are formed nearly flush, and an annular and flat plate shaped seal lip 24 is mounted on the second surface 23 so as to make extend to the first surface 22. Since the seal lip 24 abuts on the first surface 22, it is possible to prevent inner side oil from leaking to the slinger 19 side.