We consider 4D quantum dilaton gravity with the most general coupling
in a homogeneous and isotropic universe, in particular an inflationary
one, which is essentially characterized by an exponentially expanding
scale factor with time. We show that on the inflationary background t
his theory can be miraculously renormalized, at least at the one-loop
level This theory must be an effective theory during the inflation of
the un-constructed complete quantum theory of gravity.