Abstract: In an internal combustion engine, a combustion chamber is provided in a cylinder head on one side of a partition wall, and a heat-insulating layer is provided in the cylinder head on the other side of the partition wall. Cooling passages are provided in a plurality of regions provided with different heat loads in the partition wall, respectively. The flow rate of a cooling medium is set, so that the flow rate in the cooling passage existing in the region of the larger heat load is larger than that in the cooling passage existing in the region of the smaller heat load. Thus, the temperature of an exhaust gas can be maintained at a high level by maintaining the combustion chamber at a high temperature.