PURPOSE: To partition the interior of the hold of a fishing boat or the like into predetermined compartments and cool the interior of the hold efficiently by a method wherein the hold is partitioned by a single-plate type partition plate and the partition plate is provided with a passage for a coolant.

CONSTITUTION: The partition plate 9 is formed as a single plate for partitioning thef interior of the hold 3 into predetermined partitioning sizes. The partition plate 9 is provided with the passage 10 for the coolant. The passage 10 is constructed by providing a cooling pipe 11 in the inside of the hollow partition plate 9, the pipe 11 being staggered a plurality of times. Rotary eblows 14 are connected to the inlet 12 and the outlet 13 of the passage 10, and flexible pipes 15 for respectively feeding and returning the collant are connected to the elbows 14. The partition plate 9 is moved between a partitioning position and a stored position by a partition-plat holding device 17 which is provided between the plate 9 and the lateral wall surface of the hold. The interior of the hold can be cooled uniformly by holding the partition plate 9 in an errected condition and feeding the coolant from a cooling device.