Cooling device

A cooling device comprising:

• a cooling tank configured to store refrigerant liquid for immersing and cooling a heating element;
• a liquid storage tank configured to store the refrigerant liquid outside the cooling tank and having an atmosphere opening portion opening to an atmosphere;
• and
• a connector connecting the liquid storage tank and the cooling tank and allowing the refrigerant liquid to pass through the connector, wherein
• one end of the connector facing the cooling tank has a cooling-tank opening portion located in a gravity direction at a position lower than or same as a liquid level of the refrigerant liquid in the cooling tank,
• an upper portion of the cooling tank stores a gas generated in the cooling tank,
• the refrigerant liquid flows between the cooling tank and the liquid storage tank via the connector in accordance with a change in volume of the gas in the upper portion of the cooling tank,
• the liquid storage tank is provided upward of the cooling tank in the gravity direction, and
• the cooling tank and the liquid storage tank are connected only by the connector.