An alarm system for rolling shutter comprised of plurality of alarm sensors is described. An alarm sensor is comprised of a conductive wire that is threaded within a slat and is connected in both sides to slat edge elements. The slat edge elements have a moving electrical contact that can be pulled out towards the inner wall of the shutter rail by a magnet. In selected heights along the rails, on both rails, a rail electric element comprising a magnet and a rail electrical contact are installed. A wire is connected from each rail electrical contact to an alarm control box. When the slat, which includes the slat-wire, is positioned in the same height as the rail electric elements, the moving contact on the slat makes a contact with the rail electric contact, thus creating a continuous electrical circuit from one rail electrical contact, through the slat, to the second rail electric contact. An attempt to move a slat, move the rails or cut the slat, will open the electrical circuit and generate an alarm, signal. An attempt to bypass the electrical circuit is detected by the change in the line resistance.