Abstract: The fastening device is for releasably engaging a fastening element connected to one of the ends of the shoulder-strap of a handbag. The device comprises an inner plate-like element to be disposed against an inner surface of the handbag, an outer body to be disposed on an outer surface of the handbag in a position corresponding to that of the inner plate-like element, and to be fixed to the inner plate-like element on the handbag, and a slider mounted for sliding on the outer body and defining therewith a fastening seat which can be opened and closed.