  We briefly review the present status of Affleck-Dine baryo/leptogenesis
scenarios in the minimal supersymmetric standard model (MSSM) in the context of
the gravity-mediated SUSY breaking, and show that there is a serious
cosmological problem in the Affleck-Dine mechanism. That is, the late decay of
the associated large Q-balls leads to the over production of the lightest
supersymmetric particles. Then, we point out that the minimal extension of the
MSSM by introducing a gauged $U(1)_{B-L}$ symmetry naturally solves this
problem. Here, the breaking scale of the $U(1)_{B-L}$ can be determined quite
independently of the reheating temperature from the required baryon asymmetry.
It is extremely interesting that the obtained scale of the $U(1)_{B-L}$
breaking is well consistent with the one suggested from the seesaw mechanism to
explain the recent neutrino-oscillation experiments. We consider that the
present scenario provides a new determination of the $U(1)_{B-L}$ breaking
scale fully independent of the neutrino masses. We also comment on viability of
the present scenario in anomaly-mediated SUSY breaking models.
