A grip unit including holding units in each of which an upper plate is placed on a lower plate to form a V-shaped groove, a grip unit control device that can change a distance between the holding unit in a range between a distance equal to or longer than a diameter of an electrode holder with an electrode feeding mechanism and a distance equal to a diameter of an electrode, a grip unit control device moving-shaft motor that can change a height of the grip unit in a range between a height at which the holding unit are placed lower than an electrode holder brim of an electrode holder having an electrode feeding mechanism attached to an electric holder gripping device and a height to which the holding units lift up the electrode holder brim of the electrode holder having an electrode feeding mechanism attached to the electric holder gripping device, and an electrode gripping device that can grip the electrode on a lower side of the grip unit are included. In one of the pair of holding units, a portion of the upper plate which forms the V-shaped groove is placed on a front side and a portion of the lower plate is placed on a rear side so as to overlap with each other. In the other one of the pair of holding unit, a portion of the lower plate which forms the V-shaped groove is placed on the front side and the upper plate is placed on the rear side so as to overlap with each other.