PURPOSE: A tracing device for automatic welding machines which consists in forming a pair of horizontal tracing rollers in such a manner that they can roll in the welding direction while abutting on the horizontal plane of the work owing to the gravity action of vertically guiding devices and which permits efficient and highly accurate welding work.

CONSTITUTION: A horizontally moving body 4 is horizontally moved along horizontally guiding devices 3, 3' along with the extending and contracting of the air cylinder of a horizontal direction control force imparting means 10; at the same time, vertically tracing rollers 9, 9' are abutted on the vertical plane V of the work W or are retreated from the plane V. During the welding work, a travel device R is run at a fixed speed in the welding direction and while the rollers 9, 9' are being pressed onto the plane V by the pressing force controlled constant and generated from the means 10, they are rolled in the welding direction. On the other hand, while the air cylinder forming a vertically moving body lifting device 15 is extending, the vertically moving body 11 is lowered along vertically guiding devices 6, 6' owing to gravity. Hence, the horizontally tracing rollers 14, 14' are rolled in the welding direction while being abutted on the horizontal plane H of the work W only by the own weight of the moving body 11.