Corrosion of galvanized strand steel messenger wire has been investigated within Tsukumi Area Tunnel. Messenger wire has been damaged by salt contamination and leakage of water out of tunnel wall. When galvanized steel strand wire was replaced with Cr-Zr copper alloy, messenger wire has acquired corrosion resistance. Moreover Cr-Zr copper alloy strand wire ,as an exposure test piece submitted for testing within this tunnel and at Gatsugi anti-salt testing station, has also acquired corrosion resistance.