PURPOSE: To introduce only the equalized superfine drops into an ice making hopper and manufacture superfine frozen particles by providing it with a spray nozzle, a gas current passage tube, and a heat insulating vessel, which is provided at the settling point inside the gas current passage tube and transforms the superfine drops into superfine frozen particles.

CONSTITUTION: Fine water particles sprayed from the water spray nozzle 12 installed horizontally inside an ice making hopper are classified, being carried by the gas flow jetted horizontally likewise from the periphery of the water spray nozzle 12. And, only the superfine drops equal in diameter are frozen, and settle inside the heat insulating vessel 15 arranged properly at the position suited to the specified particle diameter. Hereby, drops fine and equal in diameter can be obtained. Furthermore. the speed of settlement becomes slow inside the heat insulating vessel 15, and heat conversion ratio improves, and the refrigerant gets off small, and the vessel itself can be made small.