Cooling device for internal combustion engine

A cooling device for an internal combustion engine, the cooling device comprising:

• a circulation path for a coolant, the circulation path including a water jacket of the internal combustion engine;
• a coolant temperature sensor disposed on the circulation path, the coolant temperature sensor being configured to detect a coolant temperature;
• a coolant pump disposed on the circulation path;
• and
• an electronic control unit configured to control the coolant pump based on an output of the coolant temperature sensor,
• wherein the electronic control unit is configured to execute
• processing for performing feedback control on power of the coolant pump such that the output of the coolant temperature sensor becomes a target temperature,
• micelle determination processing for determining whether or not micelles are added to the coolant based on pump work of the coolant pump and a flow rate of the coolant flowing through the circulation path,
• Toms determination processing for determining whether or not the flow rate satisfies a Toms effect expression condition, and
• correction processing for increasing a relative value of the output of the coolant temperature sensor with respect to the target temperature when the micelles is added and the Toms effect expression condition is established.