PURPOSE: To prevent the occurrence of the rattling noise caused by a guide play during a travel on an extremely irregular roadway at a high speed.

CONSTITUTION: A pair of first guides 42 are provided on the first side of a brake disk, and a pair of second guides are provided on the second side opposite to the first side. A pair of second guides are provided with pins respectively, and the pins extend in the lateral direction against the axial direction of the brake disk and are coupled with the grooves extending in the axial direction of the brake disk. A pair of first guides 42 are provided with two bolts 44. Each bolt 44 extends in the axial direction of the brake disk, has a play in the radial direction, enters each guide inner hole 50, and is centered by each ring support base 60 made of an elastic material in the guide inner hole 50. The width in the axial direction of the ring support base 60 is not larger than the diameter of the bolt 44.