To provide an offset printing method capable of performing breaking-in at start-up of printing without the use of any spoilage plate.

Prior to printing, an impression cylinder 4 separates downward from a blanket cylinder 3, and an auxiliary roller device 5 is moved leftward in the drawing by a moving means 16, so that an auxiliary roller 10 abuts against the blanket cylinder 3 and a plate cylinder 2, the blanket cylinder 3 and the auxiliary roller 10 rotate at the same circumferential speed. As the blanket cylinder 3 rotates, ink 9 transferred is moved to a position where it contacts with the auxiliary roller 10 to be partly transferred thereto. The ink 9 is immersed in a solvent 12 to be wiped by a wiping member 14, which is immersed in the solvent 12. Further, the solvent 12 adhering to surfaces of the auxiliary roller 10 is scraped by a scraper 15 to be returned to a vessel 13. Prior to printing, such operation is repeated predetermined times, so that breaking-in of ink is performed without the use of any spoilage plate.