Abstract: A door security device for preventing opening from the outside of a hinged door adjacent and normal to a wall wherein an elongate support rod has its opposite ends rotatably connected by hinges to the door. An elongate stop rod is rigidly secured at one end to the support rod at an acute angle and is adapted at its free end to engage the wall. A spacing rod is rigidly secured at its first end to the support rod and is rigidly secured at its other end to the stop rod. The door security device allows unrestricted opening of the door from either side of the door when the device is rotated to lie in a plane parallel to the door. When the device is rotated about the axis of the support rod to lie in a plane normal to the door, opening of the door from the outside is prevented by the force of the free end of the stop rod against the wall and the force against the door of the end of the support rod to which the stop rod is secured.