A variable duct apparatus that controls outside air flowing in to a radiator includes a variable louver that is provided so as to extend in the vehicle width direction between a grille opening and a radiator of a vehicle, and regulates the amount of outside air admitted to the radiator, a lower louver that is provided so as to extend in the vehicle width direction between an air inlet and the radiator, and regulates the amount of outside air admitted to the radiator, and a link mechanism that coordinates and synchronizes the variable louver and the lower louver with each other, and interrupts the coordination between the variable louver and the lower louver upon application of an external force to the lower louver to thereby permit swinging of the lower louver.