Electroly-reduced water (ERW) which is produced near cathode during electrolysis of water scavenges reactive oxygen species and protects DNA from oxidative damage (Shirahata et al., 1997). Most of cancer cells exhibit high telomerase activity to elongate telomere length, insuring their immortality. Here we found that cultivation of human lung adenocarciomaA549, human uterine cancer HeLaand human normal fibroblast TIG-1 cells were growth inhibited in medium containing ERW and drastic morphological changes occurred in A549 and HeLa cancer cells but not in TIG-1 cells. Telomerase activity did not change but telomere length became shorter depending upon cell division in medium containing ERW. Telomere binding activities of telomere binding proteins in cancer cells decreased in medium containing ERW, suggesting that ERW inhibit the binding of’ telomerase to telomere region via telomere binding proteins, resulting in the shortening of telomerelength.