One of brake pads 5 is pressed against the disc rotor D by a piston of a caliper 3 which is floatably supported on the carrier 2, and in reaction thereto, the other brake pad 5 is pressed against the disc rotor D by a claw portion 14 on the caliper 3, thereby producing a braking force. During brake release, the spring force of a return spring 22 separates the brake pad 5 from the disc rotor D. A positioning convex portion 27 is provided on the carrier 2 in a standing position adjacent to the return spring 22, and serves to restrict the sideward movement of the distal end portion of the return spring 22. Thus displacement and deformation of the return spring can be prevented, and its functions can be maintained.