PURPOSE: To always make the distance between each inking cylinder and the impression cylinder related thereto same by constitution such that a block belt is trained over four cylinders and two opposed cylinders are moved so as to be engaged with a printing unit or an image carrying web and the impression cylinder related thereto and other two cylinders are moved so as to approach and go away mutually by a tension cylinder.

CONSTITUTION: An image to be printed is formed on a block belt 4 and the block belt 4 is trained over upper and lower tension cylinders 5, 6 and printing cylinders 7, 8. A regulation member 21 regulates the position of a gear 25 in an axial direction through a bush 20 and a format gear 23 and, since the gear 25 is meshed with the spiral teeth of a central gear 24, rotation is transmitted to the printing cylinder 7 by the gear 25 when the gear 25 is displaced in the axial direction. The short shafts 29 of the tension cylinders 5, 6 are supported in a freely rotatable manner by the slides 30 guided within the grooves 31 of side plates 9,10 and regulation nuts 32 are supported on the slides 30 and threaded with screws 33, 34 and the tension cylinders 5, 6 are mutually displaced by the same quantity by the operation of a motor 39.