PURPOSE: To obtain the titled body having a constant cell ratio and good in ink absorbability, in preparing the printing face by a method wherein a mixture of synthetic resin and a fine powder is subjected to injection molding and, thereafter, the fine powder is decomposed and eluted, by preliminarily coating a mold homogeneously with the same fine powder.

CONSTITUTION: A metal salt or starches with an average particle size of 5W8μm is mixed with thermoplastic resin having a flake like or a pellet like shape in a mixing ratio within a range of 35W50% to be homogeneously adhered to the surface of the resin. On the other hand, the fine powder same to the one mixed in the resin in the kind and the particle size thereof is blown to the intaglio surface of a mold to coat the same. On this mold, the mixture of the synthetic resin and the fine powder from which moisture is perfectly removed is subjected to injection molding. The obtained relief printing plate is thrown into a hot aqueous solution well decomposing and eluting the mixed fine powder, that is, an aqueous acid solution to the metal salt or an aqueous starch degrading enzyme solution to starch to decompose and elute the fine powder into water and subsequently washed and dried to obtain an open cell printing face body.