To provide a disc rotor mounting structure which avoids the braking noises of a disc rotor in an in-plane coarse or dense mode while a conventional disc rotor mounting structure including a rubber cushion cannot avoid them.

At a disc rotor mounting site where a central portion of the disc rotor of a disc brake device is mounted on a joining portion between a wheel 1 and an axle 2, the wheel 1 has a face contact portion 1 m for face-contacting the disc rotor 3. A contact area is secured so that, when the face contact portion 1 m and the disc rotor 3 are thrust by and joined to each other by fastening a mounting-site bolt 4 to a nut 5 with a predetermined fastening force, a fastening pressure per unit area obtained by dividing the predetermined fastening force by the contact area between the face contact portion 1 m and the disc rotor 3 is a predetermined value or smaller.