PURPOSE: To hold nip pressure of rollers properly by unifying an ink roller, an ink distributing roller, and a bridge roller in a body in of detachable constitution.

CONSTITUTION: Since an ink roller 8, an ink distributing roller 10 and a bridge roller 16 are connected by connecting levers 31, 36, the detachable operation of the connecting levers is conducted collectively, and the center-to-center dimensions of the ink roller 8 and the roller 10, and the ink roller 8 and the bridge roller 16 do not change, thus resulting in no alteration of a nip pressure. Detachable operation to a dampening roller 15 of the bridge roller 16 is performed by the operation of an air cylinder 40, and the nip pressure between the ink roller 8 and the bridge roller 16 is adjusted by an eccentric holder 38. The nip pressure between the ink roller 8 and the ink distribution roller 10 is adjusted by varying the quantity of the screwing of an adjusting screw 32.