Abstract: The present specification relates to a connecting pipe connected to pipes. In one embodiment, the connecting pipe may comprise: a first opening; a second opening; and a support groove which is vertical to the transverse cross section of the first opening, and which is disposed on a first center line passing through the center of the transverse cross section of the first opening. When the connecting pipe according to embodiments is connected to the pipes, the possibility of breakage or deformation, which can occur at a connecting portion of the connecting pipe and the pipe, can be minimized.