Most of the inflation models end up with non-vanishing vacuum expectation values of the inflaton fields ��in the true vacuum, which induce, in general, nonvanishing auxiliary field G_��for the inflaton potential in supergravity. We show that the presence of nonzero G_��gives rise to inflaton decay into a pair of the gravitinos and are thereby severely constrained by cosmology especially if the gravitino is unstable and its mass is in a range of O(100) GeV \sim O(10) TeV. For several inflation models, we explicitly calculate the values of G_��and find that most of them are excluded or on the verge of being excluded for the gravitino mass in that range. We conclude that an inflation model with vanishing G_��, typically realized in a chaotic inflation, is favored in a sense that it naturally avoids the potential gravitino overproduction problem.

14 pages, 1 figure; note added about the mixing effects