Providing an overturn preventing device which has can successfully prevent an article from overturn with a simple structure. A damper of the overturn preventing device has a cylinder, a rod, and a spring. The cylinder is mounted between a top surface of a piece of furniture installed on an installation surface and a ceiling so that a direction of extension/contraction makes a predetermined angle relative to a vertical direction. The cylinder has two ends one of which is open to be formed into an opening and the other of which is closed to be formed into a bottom. The rod is inserted into the cylinder and has a distal end protruding from the opening. The spring is provided between a proximal end of the rod and the bottom of the cylinder. Two bases are rotatably coupled to the bottom of the cylinder and the distal end of the rod, respectively, and the bases abut against the top surface of the furniture and the ceiling, respectively.