A turbine hub has a through-hole extending through it in the axial direction. This through-hole is provided such that a portion of a thrust bearing covers part of the through-hole when the thrust bearing has been properly assembled onto the turbine hub, which enables assembly of the thrust bearing to be checked by the relative position relationship between the through-hole and the thrust bearing. If a portion of the thrust bearing does not cover part of the through-hole, it can be determined that either the thrust bearing is not assembled or that it has not been assembled properly.