A heat exchanger body that includes a circulation path through which a coolant is circulated and performs heat exchange between the coolant flowing through the circulation path and an electronic component; a circulation pump that supplies the coolant to the heat exchanger body; an accumulation determination unit that determines whether a foreign matter accumulation condition is fulfilled that is satisfied when foreign matter is expected to be accumulated in at least a part of the circulation path; and a process execution unit that in response to the foreign matter accumulation condition being satisfied, executes a foreign matter cleaning process of removing the foreign matter accumulated in the circulation path and cleaning the circulation path. In the foreign matter cleaning process, the process execution unit reduces an amount of coolant supplied from the circulation pump so that the coolant has a superheating degree in a nucleate boiling region.