Abstract: According to the present invention, even when a position of a printing cylinder is changed, a relative distance to a cleaning unit is invariable. Hence, a contact pressure of the cleaning unit with the printing cylinder is always kept constant. Movable plates are supported on a fixed plate and drivable in reciprocation towards and away from the printing cylinder by an actuator. A first movable plate is mounted with a positioning roller capable of rotationally contacting a bearer of the printing cylinder, thereby positioning the cleaning unit mounted on the second movable plate. The second movable plate is provided with a contact pressure adjusting mechanism of the cleaning unit. Even when changing a rotational center of the printing cylinder by the positioning roller rotationally contacting the bearer, the cleaning unit can be always set at a constant contact pressure.