PURPOSE: To provide the titled apparatus for the forming of a cold-box type core, without using a pressure vessel, particular nozzle and pump, etc., by using a nozzle to spray and atomize the triethylamine solution contained in a tank, and a perforated plate to evaporate the mist of the solution.

CONSTITUTION: The port 17a of the gassing valve 17 is shifted to connect the inlet port 24 of compressed air with the nipple 35, and the compressed air is blasted through the nozzle 33 to evacuate the hollow chamber 35a. The triethylamine solution 2 in the tank 20 is sucked through the check valve 39, and the flow-control valve 40 into the hollow chamber 35a and atomized. The atomized solution is then blasted together with compressed air toward the perforated plate 34, evaporated in the course of being passed through the perforations 34a of the perforated plate 34, and the vapor 2a is blasted toward the mold-forming sand filled in the hollow chamber 30a of the mold 30 to form a sand mold. The inlet port 24 is separated from the nipple 35 by shifting the port 14b, and compressed air is sent through the purging valve 18 to the mold 30 to purge the gas 2a from the sand mold.