A cooling apparatus 1A includes an engine 50A having a cylinder head 52A having a head side W/J 521A equipped with partial W/J 521aA through 521dA individually incorporated into four different cooling systems, first recess/projection portions P capable of generating a flow separation of cooling water in accordance with a change of the flow rate within a range of a maximum flow rate of the cooling water being provided to the head side W/J 521A, and control means for executing a control of changing the flow rate of the cooling water that flows through the first cooling medium passageway in accordance with operating conditions of the engine including a case where the control means partially changes in each of the plurality of the partial cooling medium passageways.