An electrode for an aluminum electrolytic capacitor and a method for producing the same are provided that enable improvement of water resistance of a chemical formation film having a withstand voltage of 400 V or higher.
The electrode for an aluminum electrolytic capacitor is produced by performing a hydration step of bringing the aluminum electrode into contact with a hydration treatment liquid having a temperature of 78° C. to 92° C. to form a hydrated film on the aluminum electrode and a chemical formation step of performing chemical formation at a chemical formation voltage of 400 V or higher in a chemical formation solution having a temperature of 58° C. to 78° C. to form the chemical formation film on the aluminum electrode. In this method, the amount of the hydrated film is made appropriate. In this electrode for an aluminum electrolytic capacitor, the number of voids that are exposed on a cut surface when the chemical formation film is cut is 150 voids/μm2 or smaller, and thus the water resistance thereof is high.