  Effects of soft SUSY-breaking terms on inflation potentials are discussed.
There exist generic constraints that must be satisfied in order not for the
inflaton potential to loose its flatness. We examine explicitly the constraints
in the case of a hybrid inflation model and find that the coupling constant
\lambda between the inflaton and the ``water-fall-direction'' field is bounded
as 2.0 \times 10^{-6} < \lambda. This is a highly non-trivial result. Indeed,
if we adopt the severest constraint from avoiding the problem of the gravitinos
produced non-thermally, \lambda < 7.4 \times 10^{-6} is required, under a
reasonable assumption on the reheating process. This means that the hybrid
inflation model marginally has a viable parameter space. We also discuss
analogous constraints on other inflation models.
