Abstract:I will present a derivation of the QCD axion potential by using the chiral perturbation theory. First, I will introduce the chiral symmetry breaking in QCD and show how we can construct a low-energy QCD Lagrangian, namely the Chiral Lagrangian, from the symmetry breaking pattern. Then, I will demonstrate how the axion can be included in the Chiral Lagrangian and derive the QCD axion potential. Finally, I will compare this low-energy potential with the one effective at high temperatures.