Abstract: The present invention relates to an attaching device for mounting a picture on a wall or on a similar supporting structure. The attaching device comprises a pair of magnetically attracting members, one of the members being mounted on the wall and the other of the members being mounted on the back of the picture. One of the members comprises a projecting pin adapted to fit into a seat formed on the other member for preventing the members from sliding relative to each other when they are in engagment.