  The spectrum of adiabatic density perturbation generated during inflation is
studied in the case the time derivative of an inflation-driving scalar field
(inflaton) vanishes at some time during inflation. It is shown that the
nondecaying mode of perturbation has a finite value even in this case and that
its amplitude is given by the standard formula with the time derivation of the
scalar field replaced by the potential gradient using the slow-roll equation.
