PURPOSE: To settle defects in registering precision of a print by a method wherein a substrate face is adhered temporarily to a block copy, and both ends of the block copy and an end of a plate are fixed with vices for installation of the lithoprinting plate provided with the flexible substrate to a printing drum.

CONSTITUTION: For installation of a lithoprinting plate 1 provided with a flexible substrate 0.03W0.6mm thick to a printer drum 2, the substrate face of the plate 1 is adhered temporarily at least to a part of a block copy 3 not shorten than the plate 1 in length by means of an adhesive. Then, a constituent of the block copy 3 and the plate 1 has a head 5 of the plate 1 and the block copy 3 caught by vices 4 arranged on a circumference of the printer drum 2 so that the block copy 3 comes in contact with the drum 2, the other end of the block copy 3 is fixed by the vice 4, and then the drum 2 kept in contact with a blanket drum is rotated for printing.