An object of the invention is to provide a device and a method for controlling a welding angle which is capable of resolving restrictions occurred when a conventional float type welding angle control device is used to manufacture a welded pipe, and giving full play to the ability of such a float type welding angle control device, by adopting a new mechanism for supporting and adjusting a fin roll. When the welding angle is controlled by inserting the fin roll between opposing edges of a band steel at a position located in an upstream side of squeeze rolls, the fin roll is attached to a link mechanism in which two arms are coupled so as to be pivotable within a plane defined by a pipe manufacturing line direction and a perpendicular direction thereof, and positions of gripping points of the arms are changed to adjust a position of the fin roll within the plane. Not only the mechanism of the device is simplified and an installation space can be reduced, but also the usage environment of the device and burdens for the maintenance work are considerably improved.