PURPOSE: To keep a balance of oil discharged to end faces on the inner and outer sides from the outer peripheral part of a floating bearing on the compressor side.

CONSTITUTION: A regular thrust bearing 22 and a reverse thrust bearing 23 are arranged on both sides of a thrust collar 14 mounted on a turbine shaft 6. The position of the outer end face of a floating bearing 10 on the compressor side is regulated by means of the reverse thrust bearing 23. An oil passage through which oil discharged from the outer peripheral part of the floating bearing 10 to the outer end face side is escaped to the thrust collar 14 side is formed in the reverse thrust bearing 23.