  We make an explicit formulation for the proton decay rate in the minimal
renormalizable supersymmetric (SUSY) SO(10) model. In this model, the Higgs
fields consist of ${\bf 10}$ and ${\bf \bar{126}}$ SO(10) representations in
the Yukawa interactions with matter and of ${\bf 10}$, ${\bf \bar{126}}$, ${\bf
126}$, and ${\bf 210}$ representations in the Higgs potential. We present all
the mass matrices for the Higgs fields contained in this minimal SUSY SO(10)
model. Finally, we discuss the threshold effects of these Higgs fields on the
gauge coupling unification.
