  We investigate flavor physics at present and future B factories in order to
distinguish supersymmetric models. We evaluate CP asymmetries in various B
decay modes, Delta M(Bd), Delta M(Bs), and epsilon_K in three supersymmetric
models, i.e. the minimal supergravity, the SU(5) SUSY GUT with right handed
neutrinos, and a supersymmetric model with U(2) flavor symmetry. The allowed
regions of Delta M(Bs)/Delta M(Bd) and CP asymmetries in B to J/psi K_S and b
to s gamma are different for the three models so that it is possible to
distinguish the three models by precise determinations of these observables in
near future experiments.
