Abstract: A mechanical lock type connecter of the present invention is for a plug including a non-movable member connected to a cable, and a movable member that makes relative movement in an axial direction of the cable independently from the non-movable member and the cable. The mechanical lock type connecter has arm sections for (a) holding the non-movable member in accordance with movement of the movable member in a plug inserting direction caused by inserting the plug and (b) releasing the plug by movement of the movable member in a plug detaching direction. By thus using the mechanical lock plug, provided is a mechanical lock type connecter that is capable of stably connecting the plug with the connecter and that makes it possible to downsize connecting portions of the plug and the connecter.