PURPOSE: To establish the route of a conveyance passage for a printing object freely by permitting the printing object in the course of paper discharge to be conveyed forcibly by a pair of rollers without transferring printing ink even if a surface where printing images are formed is brought into contact with the roller.

CONSTITUTION: The outer periphery 37a of a contact roller 37 is formed with prescribed surface roughness with ink repellent material. An applying means 45 is brought into contact with the outer periphery 37a to apply low surface tension liquid with prescribed thickness. The low surface tension liquid is not compatible with printing ink (b) on printing paper P after printing, so no printing ink (b) is transferred to the contact roller 37. The printing paper P is put between the contact roller 37 and a mated roller 39 to be discharged forcibly by their rotation.