Device and method for preventing rusting of cable for supporting bridge

A suspension bridge is supported by a cable having one or more cable bands. An anti-rusting device is comprised of one or more covers, each of the covers including an inner peripheral surface and covering the cable so as to leave a gap between the inner peripheral surface and an outer periphery of the cable, the gap being capable of conveying a gas along the outer periphery of the cable; and a ventilator configured to dry and feed the gas into the gap, the ventilator air-tightly communicating with the gap.