A safety socket includes a main body, a restraint mechanism and a release mechanism. The restraint mechanism includes an immovable end and a movable end. The immovable end is disposed in the main body. The movable end has a through hole. The through hole corresponds in position to one of insertion holes of the main body. The movable end has an annular protruding portion axially extending from the wall of the through hole. The annular protruding portion has a free end which is curved outward. The safety socket can prevent a plug from being disengaged from the socket by accident. The outer surface of the conductive pin of the plug won't be scraped and damaged by the wall of the through hole to enhance the service life and safety of the plug.