A cooling system including a vaporizer configured to absorb heat due to a liquid-phase refrigerant being vaporized, a condenser configured to discharge heat due to a refrigerant in a gaseous phase state being liquefied, a resistance body provided in a middle of a pipe passage ranging from the vaporizer to the condenser and applying a resistance to the refrigerant, state detection sensors provided in the pipe passage on an upstream and downstream sides of the resistance body and detecting a state of the refrigerant flowing through each side inside the pipe passage, and a flow rate controller configured to detect droplets in the refrigerant flowing through the pipe passage on the basis of a difference between detection values of the state detection sensors which are detected on the upstream and downstream sides of the resistance body, and controls a flow rate of the refrigerant on the basis of detection results.