Abstract: A safety fastener for jewelry, sports articles, leashes or the like has a casing provided with two side walls having registering openings. A locking member is slidable lengthwise between these side walls and has another opening. When all openings are in registry an article to be connected to the fastener can be inserted into the openings; when thereafter the locking member is shifted relative to the side walls of the casing, the opening of the locking member moves out of registry with the openings of the side walls and the article is locked.