Abstract: A security device includes a case for retaining an information storage device in the space between a front case and a rear case, plurality of locking sleeves protruding from the front case and the rear case, the locking sleeves is formed to engage each other in the manner that the holes of the locking sleeves are aligned in a closed position of the case, and a locking mechanism for latching the case, the locking mechanism inserted into the aligned holes of said locking sleeves in closed position of the case. The locking mechanism includes a housing, a hook which is selectively locked to the protrusion formed on the locking sleeve and released from it by extruding from the case and pulling back into the case, a moving member which is mounted on the slope and moves up and down the slope by magnetic force, while contacting with the side surface of the hook. The hook moves to the locking position or releasing position as the moving member goes up and down the slope.

Abstract: Disclosed is a locking system for cassette tape cases to prevent tapes from being stolen and to discourage theft of cases as well. A cassette tape case has configurations to lock with a locking device. The locking device case has a plate and a plurality of protrusions configured to couple with the configurations of the cassette tape case. The locking device also has slits for use in unlocking the cassette tape case. Also disclosed is an apparatus to unlock the locked cassette tape case. The unlocking apparatus includes a plurality of keys configured to be inserted into the slits of the locking device.