Supersymmetric standard model and radiative meson decay

I give a review on the generation-changing interactions of the supersymmetric standard model based on grand unification and N=1 supergravity. These interactions could make sizable effects on rare processes related to B-mesons. The decay b→sγ is discussed in particular. It is shown that the inclusive branching ratio of the radiative B-meson decay is deviated from the standard model prediction in nontrivial ranges for parameter values. ((orig.))