A loading-space protection device includes a holding unit, in which at least one winding shaft for winding up or unwinding a flexible sheet-like structure is mounted, and fastening means for securing the holding unit in a functional position, fixed on the vehicle, in mounts on the vehicle.At least one fastening means is assigned at least one securing means which is mounted moveably in the longitudinal direction of the vehicle between a blocking position, which blocks the fastening means in its fastening position within the mount on the vehicle in an interlocking manner, and a rest position, which is disengaged from the fastening means, in such a manner that severe longitudinal accelerations of the vehicle, in particular positive or negative accelerations in the form of a front or rear impact, lead to the securing means being displaced into the blocking position.