PURPOSE: To achieve a handy and easy exchange of plates with a shorter plate exchange time by moving a plate vice base on the rear gripping side horizontally by a specified means to load or unload a plate on the surface of the plate cylinder.

CONSTITUTION: A horizontal notched surface 21 is provided on a shaft 20 internally provided between the plate cylinder 12 at a notch A thereof and a plate vice base 2 on the rear gripping side. When the notched surface 21 of the shaft 20 is turned upward, the circumference of the shaft 20 is sticks out to contact a bolt 10 for stopper causing the plate vice base 2 to move to the right. With the rotation of the shaft 20 by 90° to the right, the horizontal notched surface 21 is shifted to the plate cylinder notch a and the bolt 10 is moved to the left by the portion of the notched surface to shift the plate vice base to the left accordingly.