To reduce the generation of a bearing pressure exerted on a coupling part between the hub of a brake disc and a brake ring.

The coupling part 21 of a hub 2 and the coupling part 31 of a brake ring 3 are stretched in such a manner to be axially lapped with each other, and a mounting hole 4 is formed in the hub 2 side and a square hole 5 is attached on the brake ring 3 side. A pin 6 is provided with a square column part loosely fitted in a square hole 5 below a flange 61; and a shaft part fitted in a mounting hole 4, and the end part of the shaft part is caulked. Since contact between the square hole 5 and the square column part of the pin 6 is brought into a surface contact, a bearing pressure is reduced and durability is improved.