PURPOSE: To improve a thermal efficiency by adding partitions which allow brine to pass through but reject a lump of ice in the brine in openings respectively provided at a cooling passage and a circulating passage.

CONSTITUTION: A brine taking-out unit of a cooling passage 2 has a plurality of tubes 4, and a brine taking-out unit of a circulating passage 3 has a plurality of tubes 6. Partitions 9 which allow brine to pass through but reject a lump of ice in the brine are provided in an opening 41 of each tube 4 and an opening 61 of each tube 6. Thus, there is no fear that a pump becomes an overload state due to blocking of the opening 61 to a sealed state or the lump of ice is introduced into the pump to damage the pump, and an ice cold storage tank 1 can be fully stored that much with fine particles of ice to increase storage capacity of the tank 1. Thus, its thermal efficiency is improved.