The present invention relates to a joining method, a joining apparatus and a joining agent capable of joining two bodies to be jointed in a large size or in a complicated shape in a good joining condition. Specially, the present invention is to provide an improvement in a control of the current supplying method applicable for the electrically heating of the ceramic bodies or a joining agent in an electric conduction (a elecrode switching type due to a plurality of fixed electrodes and a switching control type between two kinds of the electric power sources), a control method of a auxiliary heating, a control of the holding apparatus (the control by the free thermal expansion at the pre-heating, a adaption of a balance mechanism and a measurement of the displacement), the adjustment of the shape at the butted portion (improvement of the pipe joint structure) and a joining agent superior in the joining strength.