PURPOSE: To prevent a failure of printing due to the transferring slippage of a corrugated sheet by a method wherein not the speed of a printing cylinder but that of a transferring part is changed in the multi-color printing line of the corrugated sheet.

CONSTITUTION: In the printing line of corrugated sheet, in which a plurality of printing parts 4A and the like consisting of a printing cylinder 3 and an impression cylinder 10 driven through a main driving system 20 are arranged and the transferring part 9A and the like of corrugated sheet 2 driven through a sub-driving system 30 is arranged between the respective printing parts 4A and the like, a differential gear 40, which can change the speed of an upper and a lower conveyor belts 8 and 7 composing of the transferring part 9A of the corrugated sheet, is provided on the sub-driving system 30 side. When the transferring slippage of the corrugated sheet develops at the transferring part 9A, the transferring slippage is detected so as to correct the transferring slippage by controlling the speed of the transferring part 9A through increase and decrease by actuating the differential gear 40 in order to transfer the corrugated sheet to the printing part 4A, which rotates at constant speed.