To simply and surely prevent a ground stain of a plate without necessitating a temperature control of the plate, in regard to printing for which a plate material dispensing with dampening water is used.

A layer of a barrier liquid 12 not showing compatibility with a resin which ink 10 contains is formed on the surface of the layer of ink 11 of an inking roller 10, as shown in Fig. 1 (A). Then the ground stain of the surface of the plate 20 can be prevented, since the layer of the barrier liquid 12 exists between the ink 11 and the plate 20. When the barrier liquid 12 is dispersed like particles on the surface of the layer of the ink 10, as shown in Fig. 1 (B), both the prevention of scumming of the plate 20 and the stability of inking on the plate 20 can be attained together.