Abstract: The present invention comprises weld units A, A' which move on a bottom plate 101 along standing plates 102, moving tables B which hold cables 6 extending from said welding units A, A', detectors C, C' which detect moving directions of the welding units A, A', and a control circuit part D which controls motors 32, 35 so as to cause the X-Y tables B to move and follow the movings of the welding units A, A' by signals issued from the detectors C, C'. Therefore, when the motors 2 are driven to rotate rollers 4, the welding units A perform the weldings on connecting parts (a) between the standing plates 102 and a bottom plate 101 while the welding units A move along the standing plates 102. The detectors detect the moving directions of the welding units A, and are controlled by signals issued from the detectors so as to cause the cables 6 to follow the welding units A, while the moving tables B follows the welding units A.