  We show that the smooth hybrid inflation is naturally realized in a framework
of supersymmetric axion model. Identifying the Peccei-Quinn scalar fields as a
part of the infaton sector, successful inflation takes place reproducing the
amplitude and spectral index of the curvature perturbation observed by WMAP. A
relatively large axion isocurvature perturbation and its non-Gaussianity are
predicted in our model. The saxion coherent oscillation has a large amplitude
and dominates the Universe. The subsequent decay of the saxion produces huge
amount of entropy, which dilutes unwanted relics. Winos, the lightest
supersymmetric particles in this scenario, are produced non-thermally in the
decay and account for dark matter.
