Cooling system for internal combustion engine

A cooling system for an internal combustion engine, including a radiator provided in a coolant circulation path of the internal combustion engine, and an actuator that controls a flow rate of a coolant that passes through the radiator, wherein the actuator is controlled so that a coolant temperature of the internal combustion engine becomes substantially equal to a target coolant temperature, comprising:

• a calculating unit that calculates a cooling loss as a quantity of heat removed from the internal combustion engine and received by the coolant, based on an operating state of the internal combustion engine, and calculates a required radiator flow rate, based on the cooling loss, the target coolant temperature, and a temperature of the coolant that has passed through the radiator, the required radiator flow rate representing a quantity of the coolant required to pass through the radiator so as to make the coolant temperature substantially equal to the target coolant temperature;
• and
• a control unit that controls the actuator based on the required radiator flow rate obtained by the calculating unit.