  We study the cosmological consequences of generic scalar fields like moduli
which decay only through gravitationally suppressed interactions. We consider a
new production mechanism of gravitinos from moduli decay, which might be more
effective than previously known mechanisms, and calculate the final
gravitino-to-entropy ratio to compare with the constraints imposed by
successful big bang nucleosynthesis (BBN) etc., taking possible hadronic decays
of gravitinos into account. We find the modulus mass smaller than $\sim 10^4$
TeV is excluded. On the other hand, inflation models with high reheating
temperatures $T_{R,\rm inf} \sim 10^{16}$ GeV can be compatible with BBN thanks
to the late-time entropy production from the moduli decay if model parameters
are appropriately chosen.
