A rustproof cover for an automobile disk brake which is attached to a surface portion of a disk portion of a automobile wheel so as to shield a plurality of penetration portions penetrating the disk portion in a direction from the surface portion of the disk portion to a rear-surface portion thereof, the rustproof cover comprising, a recessed portion which is recessed from the surface portion of the disk portion to the rear-surface portion thereof so as to follow the shape of each penetration portion, wherein each recessed portion includes a protrusion portion which engages with a rear surface of the disk portion at the rear-surface portion of the disk portion so as to prevent a separation of the rustproof cover, and wherein the rustproof cover is formed of a flexible resin.