  The effects of the gravitational back reaction of cosmological perturbations
are investigated in a phantom inflation model. The effective energy-momentum
tensor of the gravitational back reaction of cosmological perturbations whose
wavelengths are larger than the Hubble radius is calculated. Our results show
that the effects of gravitational back reaction will counteract that of the
phantom energy. It is demonstrated in a chaotic phantom inflation model that if
the phantom field at the end of inflation is larger than a critical value
determined by the necessary e-folds, the phantom inflation phase might be
terminated by the gravitational back reaction.
