PURPOSE: To enable a large amount of items to be freezed and stored by a method wherein cold heat accumulating agent filling case capable of performing a heat exchanging operation with cooling medium liquid of a freezing device for freezing and keeping the freezed items is arranged within a liquid tank.

CONSTITUTION: A propeller 16 is rotated by a motor 17 of an agitating device 15 so as to agitate brine 13. During this operation, an evaporator formed by heat exchanging tubes 14 is operated to cool the brine 13. A temperature in which the brine 13 is cooled is set to be a value in which a cold heat accumulating agent 41 is freezed through a heat exchanging operation with the cold heat accumulative agent 41 in a case 40. In addition, when a temperature of the brine reaches the set temperature, operation of the heat exchanging tubes 14 or the agitating device 15 is turned off. As the temperature of the brine 13 is increased to reach a freezing temperature of the cold heat accumulative agent 41, the heat exchanging tubes 14 and the agitating device 15 are turned on again. Through this repetition, a heat exchanging operation between the brine 13 and the cold heat accumulative agent 41 is activated and even if a large amount of freezed items are fed, they can be cooled.