PURPOSE: To improve the printability, particularly ink receptivity of the printing plate by photopolymerizing the photopolymerizable composition coated in the synthetic resin printing plate having relief images and grafting the same on the surfaces of the raised parts of the printing plate.

CONSTITUTION: The organic solvent solution of radical polymerizable monomers such as (metha)acrylic acids, styrene (derivative), vinyl pyridines, etc. and photosensitizing agents such as benzoin ethter, acetophenone, etc. is coated on the synthetic resin printing plate having relief images and is then dried, whereby the film of about thickness 0.1 to 50μ is formed. Next, active rays are radiated from the film side by the photopolymerizable composition to graft-polymerize the radical polymerizable monomer to the raised parts of the printing plate, after which the unreacted non-graft matter is removed by using a solvent, whereby the printing plate is formed.