A film F in the form of a belt which is provided in a manner to be fed out and wound up is wound on a trap roller 11 which is provided opposite to a blanket 4 of a blanket wheel 3 via a contacting and withdrawing mechanism 12. The film F is caused to contact the blanket 4 to remove surplus ink or blurring ink. By this arrangement, ink trap can be made by contacting an always clean film and ink trap can also be made with a simple mechanism for contacting and withdrawing the trap roller.