Immersion cooling device

An immersion cooling device that cools a heating element provided on a board, the immersion cooling device comprising:

• a casing group including inclined casings, each of which has a box shape extending downward toward a first side in a horizontal direction and each of which is configured to accommodate the heating element, and configured by arranging the inclined casings in an up-down direction;
• a supply-side header extending in the up-down direction on a second side in the horizontal direction of the casing group and configured to introduce a first refrigerant into each of the inclined casings;
• a discharge-side header extending in the up-down direction on the first side in the horizontal direction of the casing group and configured to receive introduction of the first refrigerant from each of the inclined casings;
• a refrigerant pumping unit configured to pump the first refrigerant from the discharge-side header to the supply-side header;
• and
• a heat exchange unit configured to cool the first refrigerant by exchanging heat between a second refrigerant supplied from an outside and the first refrigerant.