The effects of the cavitating jet on the corrosion resistance of carbon steel are discussed. It is well-known that there is an incubation period without loss of any mass in the initial stage of exposure to cavitation. The cavitating flow is also a high-speed multiphase flow, however, it produces the mechanical and thermal effects. These effects significantly influence the corrosion resistance of metals. In order to demonstrate the improvement of the corrosion resistance by the cavitating jet, the corrosion property of carbon steel was evaluated experimentally by measuring the corrosion potential for three different conditions.