A surface treatment layer 11 is formed on a surface 10 of a through-hole 1 so that the surface 10 has an angle X of contact with solution L which is smaller than an angle Y of contact of a die 2 per se with the solution L. When the solution L is applied, the wetting action of the solution L relative to the through-hole 1 is improved so that the solution L can be extended over the surface treatment layer 11, eventually over the entire surface of the through-hole 1. Consequently, the entire surface thereof can be formed with a crystallized layer by performing water evaporation. As a result, molding at higher temperature can be realized, and high-density compacts can be stably obtained. Further, the solution L in which the lubricant is dissolved in a solvent into a homogeneous phase, is applied to a molding portion 1A, and then evaporated to thereby form crystals thereon, thus forming the crystallized layer.