The invention relates to a rear protection mechanism with a magnetic opening system, intended for objects used to hold elements, such as, for example, briefcases, backpacks or suitcases, said mechanism acting as an anti-theft system for rear, side and/or lower pockets on said objects. The rear mechanism with a magnetic opening system (positioned against the user's body) consists of flaps with non-visible magnets located inside said flaps, which, upon coming into contact with other magnets located on the rear surface of the object, generate an attraction that secures the flaps, such as to prevent third parties from gaining access to pockets on the outside of the briefcase, backpack or suitcase. The invention also relates to a system of self-adjusting straps that allow the weight or load contained in the element-holding object.