Abstract: A device to prevent the unauthorized removal of a closure from the mouth of a bottle having an annular ring adjacent to the mouth about the bottle neck. A cap portion fits over the end of the bottle neck and receives within it the annular ring, the bottle mouth and the closure. A locking mechanism housing is formed adjacent the cap and communicates with the bore in the cap by means of a slot. In a first embodiment a pawl means is pivotally mounted in the housing and is spring biased to extend through the slot into the bore. A second embodiment uses a cam controlled spring mechanism to slideably position pawl means in the cap portion or withdraw it therefrom. A tapered leading edge of the pawl means causes the pawl to be displaced into the housing as the annular ring of the bottle passes the pawl. The spring forces the pawl in behind the ring to prevent removal of the cap.