PURPOSE: To join a preceding material and succeeding material without welding by press-contacting with overlapping the tip of the following sheet bar which was descaled to the rear end of the preceding sheet bar removing a scale.

CONSTITUTION: A slub is made to a sheet bar by rolling with a rough rolling mill and a scale is removed by a scale removing device 1 and fed to a sheet bar overlapping device 3 by a pinch roll device 2. The tip of the succeeding sheet bar overtakes the preceding sheet bar being rolled by a finishing rolling mill 5 with being fed at the prescribed speed on the roller table 3b of the sheet bar overlapping device 3 and is overlapped after its positioning. When the rear end of the preceding sheet bar and the tip of the sheet bar of the rear end are overlapped to the prescribed quantity, the rotation speed of the pinch roll device 2 is controlled, the sheet bar is synchronized and fed to the down stream, the overlapping part is press-contacted by being pinched by a press-contacting roll 4a at a press-contacting device 4 and is rolled to the prescribed dimension by the finish rolling mill 5.