A removable tailgate gap cover for preventing ingress of debris in a tailgate gap. The gap cover comprises an elongated cover plate having a top surface, a bottom surface, two longitudinal edges and an elongated support bar having an upper end and a lower end, wherein the upper end is fixedly attached to and substantially centrally aligned with the lengthwise direction of the bottom surface. The elongated support bar comprises a magnetic attaching means disposed along the lower end of the elongated support bar for attaching the gap cover to the floor of the end portion of the truck bed.