PURPOSE: To preserve ceramic composition for plastic molding for a long time without impairing moldability by mixing and kneading an organic substance binder with nonoxide-based ceramic powder and preserving the produced ceramic composition for plastic molding in the environment of the specified relative humidity and temp.

CONSTITUTION: An organic substance binder is mixed and kneaded with nonoxide-based ceramic powder. The produced ceramic composition for plastic molding is preserved in the environment of ≤50% relative humidity at 0-30°C. Further nonoxide-based ceramics are constituted of the compds. free from oxygen. As embodiment, silicon nitride (Si3N4), aluminum nitride (AlN), boron nitride (BN) and silicon carbide (SiO), etc., are shown. Further as the organic substance binder, various substances can be utilized which incorporate thermoplastic resin such as polystylene and PE and paraffin, etc., as a main component and furthermore light oil and a surfactant in addition thereto. Thereby ceramic composition constituted of nonoxide-based ceramics can be preserved for a long time without impairing molding characteristics such as fluidity.