Abstract: A flange face portion located radially outwardly of boltholes of a flange is formed as a tilting face so that a maximum oppositely-spaced distance ? of the flange face portion from a disc rotor is preferably 10 ?m. Thereby, minimization is implemented for convex deformation of an outer circumferential end portion of the flange when bolts are press-inserted into boltholes, when nuts are tightened onto bolts, tightening forces compress the disc rotor and the flange to be in close contact and to be fixed-via planar surfaces thereof without clearance being formed therebetween. Consequently, the accuracy of side run-out with surface of the flange can be prevented from being deteriorated.