PURPOSE: To freeze efficiently a sample by providing a rotary support disk in a refrigerant tank, fitting plural metallic blocks to the support disk in a free elevation state, and freezing samples on the blocks to change blocks in succession.

CONSTITUTION: The rotary support plate 69 is provided in the refrigerant tank 36 and plural circular holes 70 are bored therein. Flanged metallic blocks 33 are inserted into the circular holes 70, supported with elastic support pieces 73, and held on a liquid surface (b). When the support plate 69 is rotated up a certain place, the elastic support body 73 is pushed with a collision piece 74 and detached, and the metallic block 33 is inserted into the circular hole 70 up to its flange 72. A sample 34 is put in a holder 59, which is lowered vertically to place the sample 34 on the top surface of the block 33 while the block 33 is supported with the elastic support body 73; and the block 33 is inserted into the circular hole 70 up to its flange 70, and the sample 34 is frozen quickly in the liquid below the refrigerant level (b). Thus, plural metallic blocks need not be replaced one after another and neither the removal of liquid drops nor the defrosting of the top surfaces of the metallic blocks before use is required, thereby improving the efficiency.