Disclosed is an invention related to a packing cylinder for an expansion joint. A packing cylinder for an expansion joint, disclosed in the present invention, comprises: a main packing body having a through hole that forms an injection path for a packing material, having a pressure ball portion that is movably injected into the lower end of the through hole so as to open and close the through hole, and having a supporting member for preventing the pressure ball portion from falling out; and an auxiliary cylinder having on the lower side thereof an injection port to be detachably attached to the main packing body such that the packing material is injected through the through hole of the main packing body, having the central part thereof form an injection path, and having the upper part of the injection path open and close by means of a plug portion.