To provide a method for fitting a printing plate which enables sure and easy fitting of a pliable press plate to a plate cylinder and reduces elongation of the press plate to 100 μm or less.

The present device is equipped with a printing plate pressing mechanism 17 which brings a notch of the plate tip of the press plate 70 into contact with a positioning pin 14 of a plate tip clamping mechanism 12, fixes it to the pin and presses the press plate 70 on the outer peripheral surface of the plate cylinder after fixing, a plate back fixing mechanism 13 and a block copy sheet 27 which is wound around on the plate cylinder and fixed thereon and has a plate slippage preventing function. Elongation of the printing plate in the direction of rotation of the plate cylinder on the occasion of fitting the plate is made 100 μm or less, while a projecting part indenting the rear of the printing plate by bringing the block copy sheet 27 into pressure contact with the rear of the printing plate is provided on the surface. A projection constituting the projecting part comprises a plurality of particle groups and the average particle size of the particle group of which the particle size is larger than the intermediate value between the maximum particle size and the minimum is twice or more as large as the average particle size of the particle group of which the particle size is smaller than the intermediate value, while the hardness of the particle of the average particle size of the particle group having a larger particle size than the intermediate value is higher than that of the particle of the average particle size of the particle group having a smaller particle size than the intermediate value. The height of the projection constituted of the particles of the average particle size of the particle group having a larger particle size than the intermediate value is in the range of 5-50 μm.