A dustcover used in a disc brake of a vehicle for covering a disc rotor disposed in a wheel disc of cup shape from the opposite side of the wheel disc so as to protect the rotor from splashed mud water. The dustcover is provided with a pair of vent openings respectively open to the frontward direction and the rearward direction of the vehicle formed thereon at a lowered portion thereof than the rotational axis of the rotor. An air collecting portion is formed at the frontwardly open vent opening, gradually expanding in the air flowing area in the frontward direction of the vehicle. The front end of the air collecting portion is projected out of the cup-shaped wheel disc. The air collected by the air collecting portion is allowed to pass rearwardly through the dustcover right along the lower half portion of the rotor for cooling it.