The influenced of condensed water on an EGR device is alleviated. A device (100) that controls a cooling system including adjusting means for being able to adjust a circulation amount of coolant in a first flow passage, including an engine cooling flow passage, an EGR cooling flow passage and a radiator flow passage, and a second flow passage, including the engine cooling flow passage, the EGR cooling flow passage and a bypass flow passage and not including the radiator flow passage, includes: measuring means for measuring a temperature of the coolant; limiting means for limiting circulation of the coolant at starting an internal combustion engine; and control means for circulating the coolant preferentially through the second flow passage via control over the adjusting means based on the measured temperature in a period in which circulation of the coolant is limited.