The invention concerns a device for securing a back cover on a middle part of a watchcase, characterized in that it includes an intermediate element to which the back cover is connected, said intermediate element being screwed onto the middle part of the watch, means being provided to allow the back cover to drive the intermediate element in rotation until the latter reaches a locked position on the middle part, the back cover also being able to be pivoted relative to the intermediate element without the latter being unscrewed for alignment with the 12 o'clock-6 o'clock axis of the watch.