PURPOSE: To uniformize the film thickness of the ink transferred to printing paper, to reduce the spoilage due to trial printing, to conserve labor and time for adjustment and to limit the effect on printing quality to the min. range.

CONSTITUTION: When both surfaces of printing paper are printed at the same time in such a state that the printing paper is held between two blanket cylinders 101, 102, the surface temp. of the paper winding blanket cylinder 101 and that of the paper release blanket cylinder 102 are held so that the former becomes low to perform double-side printing. At this time, cooling means 1-3 cooling the surface of the paper winding blanket cylinder 101 and heating means 4-7 heating the surface of the paper release blanket cylinder 102 are controlled by a control means to hold the surface temps. of both blanket cylinders 101, 102 to the temp. difference corresponding to the dot area ratio difference of both surfaces of printing paper.