Abstract: The invention provides a pressure relief device for aerosol containers that may be subject to high internal pressures. The pressure relief device is a small plug formed of a rubber material. The plug has first and second bores extending inwardly from each end and defining between them a thin integral diaphragm separating the bores. A groove extends circumferentially around the device, and one end of the device is tapered so that it can be forced into a hole in the bottom of an aerosol container. The area and thickness of the diaphragm can be varied to control the pressure at which the diaphragm will rupture to relieve excess pressures in the container. The rupturable diaphragm is protected from damage during the insertion process, and when the container is on store shelves, by being located near the center of the device, protected by the bores on each side of the diaphragm.