PURPOSE: To prevent the contamination of the environment caused by dusts and noise, further to improve the safety for the shaking out, by infiltrating an alcoholic solution or the aqueous solution containing surfactant to the mold, separating the castings and the casting sand from the casting frame.

CONSTITUTION: The molten metal is poured in the casting mold 1a, 1b molded by using the casting sand 2 which is added with the self-curing type resin and the organic sulfonic acid base curing agent, etc. After it is left standing and cooled in the prescribed time, the total or a part of the casting mold is infiltrated with the alcoholic solution or the aqueous solution containing surfactant, the binding force of the casting mold 1a, 1b is weakened. Sometimes, this casting mold is heated quickly in a short time, the alcoholic solution or the aqueous solution containing surfactant is evaporated, and it is filled in the gap among the casting sand granules of the mold. Therefore, the strength of casting mold can be dropped remarkably compared with the strength just after the casting mold is cooled. If the separating device of the pressurizing device, etc., as the assisting means for shaking out the frame in the state that the casting mold strength is reduced, the generation of noise, vibration and dusts is eliminated, and the contamination of environment is improved.