PURPOSE: To enable to perform a printing on the back as it is without the need for turning-over and transferring work, by a method wherein a press drum, a blanket drum, and a plate drum are placed in said order to form a sheet offset printer for back printing provided with a print unit.

CONSTITUTION: A print unit 30 is constituted such that a press drum 32, a blanket drum 33, and a plate drum 34 are situated in the order named, and the constitution performs a printing on the back of a printing sheet 1. In the case of a multicolor printing, an intermediate drum 35 is located between the print units 30, 30. The final unit 30 is provided with sheet removing drums 35 to hold the multicolor printed sheet 1 therebetween, and the print sheet 1 is further held between the nip formed by a chain 41 stretched about a delivery wheel 40. An ultraviolet drier 45 dries it while it is being conveyed in a manner being held between the nips formed by the chain 41.