To easily bend a metallic tube into the desired shape without changing its sectional shape.

A hollow metallic tube 1 and a seal member 2 to be arranged on the end part of the metallic tube 1 are provided, the heat-melting material 7 which is heated to be melted in advance is filled in the metallic tube 1, the heat-melting material 7 is hardened by cooling the metallic tube 1 at the temperature below the melting point of the heat-melting material 7, and then, the metallic tube 1 is bent while it is heated at the temperature close to the melting point of the heat-melting material 7, and the metallic tube 1 is re-heated to re-melt the heat-melting material 7 and discharge it.