PROBLEM TO BE SOLVED: To provide a tube fusing method, even when using materials such as a thick-wall tube and a thin-wall tube, the heat transmission of which are different, capable of providing a same fusion state.SOLUTION: The method of fusing a first tube 12 and a second tube 11, includes a melting step of heating a joining part 13 of the first tube and the second tube in a state where a cored bar 51 is positioned in the second tube, where at least a part thereof is inserted in the first tube, and then rotating the cored bar around an axis with respect to the second tube. During the melting step, heating control of the joining part is performed on the basis of a change in axial rotation torque of the cored bar.SELECTED DRAWING: Figure 4【課題】肉厚、肉薄チューブのような熱の伝わり方が異なる材料を用いた場合でも同じ融着状態が得られるチューブ融着方法を提供する。【解決手段】第１のチューブ１２と第２のチューブ１１とを融着する方法であり、第１のチューブ内に少なくとも一部が挿入された第２のチューブ内に芯金５１を位置した状態で、第１のチューブと第２のチューブとの接合部１３を加熱しながら、第２のチューブに対して芯金を軸周りに回転させる融解工程を有し、融解工程中において、芯金の軸回転トルクの変化に基づいて、接合部の加熱制御をおこなう。【選択図】図４
