To provide a copper ion-generating apparatus which peels off and inhibits generation of rust, scale or slime in various water-related equipment such as a cooling tower and is excellent in bactericidal and algicidal properties.

The copper ion-generating apparatus 2 is equipped with a casing 21 having a water intake port 213a and a drainage port 213b wherein liquid taken in from the intake port 213a is passed through its interior and drained out from the drainage port 213b, a copper anode 23 installed in a prescribed position in the casing 21 and a cathode 22 installed facing the copper anode 23 at a prescribed distance from the copper anode 23 in the casing 21. An operation box 3 serving as an external power source applies positive and negative potentials between the copper anode 23 and the cathode 22 to generate copper ion from the copper anode 23.