To obtain an aluminum alloy having a sufficiently base anode potential and a sufficiently large electricity generation quantity as using a corrosion environment in a reinforced concrete structure by containing Zn, Bi of a specified weight ratio and the balance Al with inevitable impurities.

In an aluminum alloy contains 7.0-50.0 wt.% Zn and 0.01-0.60 wt.% Bi, an electricity generation quantity is increased as well as an anode potential is maintained well because Zn and Bi has a function to suppress self- dissolving of the alloy. In the case of <7.0 wt.% Zn or of <0.01 wt.% Bi, a function to increase an electricity generation quantity is not sufficiently demonstrated and then an electricity generation quantity is lowered. Further, when Zn exceeds 50 wt.% or Bi exceeds 0.60 wt.%, an anode potential is likely turned to noble. Thus, the alloy, in which an electricity generation quantity is large e.g. 1470 A×hr/kg, and an anode potential is ≤1200 mV as base, is suitable for reinforcing bar of a reinforcing concrete structure.