This invention provides an arrangement wherein members, such as a guide tube, feed rod, air cylinders, and parts feeding control unit, which perform the parts feeding function, are supported with good balance to ensure that a part is inserted in a receiving hole in a mating part, for example a hole in a movable electrode, accurately and with high reliability.The basic arrangement comprises a guide tube 1 joined to the lower side 16 of a base plate 14, an air cylinder 29 attached to the upper side 19 of the base plate 14, and a stationary member 31 to which the air cylinder is firmly joined.