PURPOSE: To rapidly freeze while preventing cracking by making the temperature of a refrigerating liquid lower by a specified temperature than that of a material to be frozen before refrigeration.

CONSTITUTION: The temperature T (°C) of a refrigerating liquid is controlled within a range of temperatures lower by 20 to 40°C than the temperature t (°C) of a material to be frozen before refrigeration. Exactly, the treatment is carried out by using a refrigerating liquid of a temperature within the range of t-T≤35 (°C). Thereby, a thick material to be refrigerated can be prevented, e.g. from cracking and a flexible food exhibiting a high water content, e.g. devil's tongue can also be rapidly frozen.