Abstract: A security device for protecting electronically-stored data comprising a protected circuit board which has a memory device for storing data code and a battery, a plurality of protective circuit boards respectively overlaid on each side of the protected circuit board, and a plurality of connectors connected between the protected circuit board and the protective circuit boards, wherein the printed circuit on each protective circuit board is respectively connected to the printed circuit on the protected circuit board forming into a series electronic circuit. Detaching either protective circuit board from said protected circuit board or damaging either protective circuit board will break the series electronic circuit causing any code data stored in the memory device to be erased.