PURPOSE: To stabilize the welding condition and to manufacture the thin wall tube with execellent quality by transferring the welded tube in the state of insert-supporting from both sides.

CONSTITUTION: The welded tube 20 butt-welded with a welding torch 13 is transferred with a transferring device 16. On this transferring device 16, plural slide rails 30 are bridged on the chain 21, 22 of a catapillar running with the same speed to the transfer and a pair of chucks 31, 32 are set freely movable. The chuck 31, 32 are the straight surface 37 paralleling with the transferring route and the side guides 33, 34 are set so as to insert and support the welded tube 20 without slipping. With this device, because the vibration and the impact for feeding the welded tube is eliminated, so the welding condition for the blank tube stock positioned to the welding position is stabilized. On the result, the products have the constant bead shape and is execellent roundness, so the treatment and the work on the post stage are made easy.