Abstract: A door lock security device is disclosed for locking over the shaft of a door lock rotary knob or a door knob. The device comprises an inner cover which is further comprised of first and second shell portions having an opening between them for closing around the shaft of the door lock rotary knob or door knob, an outer cover which substantially encompasses and overlaps the inner cover to sufficiently shield the inner cover to prevent tampering, and a lock for releasably securing the outer cover to the inner cover. When the inner and outer covers are engaged together around the shaft they prevent the door lock rotary knob or the door knob from being manipulated from a closed to an open position. In one embodiment the first and second shell portions of the inner cover are hingedly attached along one edge while in a further embodiment the first and second shell portions are releasably secured together in a closed position at an opposite edge by a clasp.