  The connection between the axion and right-handed neutrinos is explored in
the framework of the minimal SUSY SO(10) model. The former is related to the
Peccei-Quinn (PQ) solution to the strong CP problem and the latter is to the
light Majorana neutrinos through the see-saw mechanism. In this model, a
relative phase between $({\bf 10,1,3}) (\equiv {\bf \bar{\Delta}}_R) \subset
{\bf \bar{126}}$ and $({\bf \bar{10},1,3}) (\equiv {\bf \Delta}_R) \subset {\bf
126}$ multiplets of ${\rm SU}(4) \times {\rm SU}(2)_L \times {\rm SU}(2)_R
\subset {\rm SO}(10)$ becomes a physical degree of freedom identified with the
axion. Then, the PQ symmetry breaking scale ($\Lambda_{\rm PQ}$) and the $B-L$
symmetry breaking scale ($\Lambda_{\rm B-L}$) coincide through the VEV of ${\bf
\bar{\Delta}}_R$. The scalar partner of the lightest right-handed neutrino is
regarded as the inflaton, which gives a consistent density fluctuation for the
CMB.
