  A pseudo Nambu-Goldstone boson as curvaton avoids the eta-problem of
inflation which plagues most curvaton candidates. We point out that a concrete
realization of the curvaton mechanism with a pseudo Nambu-Goldstone boson can
be found in the supersymmetric Peccei-Quinn mechanism resolving the strong CP
problem. In the flaton models of Peccei-Quinn symmetry breaking, the angular
degree of freedom associated with the QCD axion can naturally be a flat
direction during inflation and provides successful curvature perturbations. In
this scheme, the preferred values of the axion scale and the Hubble parameter
during inflation turn out to be about 10^{10} GeV and 10^{12} GeV,
respectively. Moreover, it is found that a significant isocurvature component,
(anti)correlated to the overall curvature perturbation, can be generated, which
is a smoking-gun for the curvaton scenario. Finally, non-Gaussianity in the
perturbation spectrum at potentially observable level is also possible.
