Provided is a device for fastening and unfastening a watch, in which a plurality of bezels is provided and a fastening means is provided between the bezels, so that the watch is easily and conveniently fastened and unfastened in a one-touch manner, thus completely preventing the bezels from being damaged, and providing a novel structure for fastening and unfastening a wrist watch, unlike a general watch that has a fastening and unfastening structure on a watch band. Therefore, it is possible to solve problems of inconvenience when fastening and unfastening a watch band on a user's wrist because the fastening structure applied to the band in the conventional wrist watch is eliminated, in addition to offering good appearance and allowing the watch to be easily detachably attached.