PURPOSE: To enable an article having complicate inner configurations to be manufactured relatively easily at low cost by immersing a green body injection- molded in a state of being incorporated with a placement core into an organic solvent and then dissolving the placement core therein.

CONSTITUTION: A placement core 3 is disposed in a mold 5 for injection molding, and the kneaded body of alumina powder and binder is injection-molded in order to be a green body 6 in a state of including the placing core 3. Then the green body 6 is immersed in an organic solvent 7, such as e.g. methylene chloride, and after the lapse of time of 10 hours at a room temperature of 25°C, the green body is taken out for excluding the placing core 3 therefrom perfectly. Next, it is placed in a heating furnace and degreasing is effected therefor, following this, baking is performed therefor, resulting in obtaining a non-defective article 1.