Disclosed is an apparatus for replacing a welding tip for spot welding. In an exemplary embodiment of the present invention, the apparatus for replacing a welding tip for spot welding includes a post installed in a workplace having a spot welding machine with upper, and lower welding guns provided thereto, a base plate mounted on a top of the post, a welding tip removing unit mounted on one side of an upper side of the base plate for clamping and removing a spent welding tip mounted to the upper welding gun or the lower welding gun by operation of a cylinder, a holder unit mounted on the upper side of the base plate spaced from the welding tip removing unit, and a welding tip cassette mounted to the holder unit in a state new welding tips to be mounted to the upper, and lower welding guns are set in an upper side and a lower side thereof.