  Measurability of generation mixing is studied on the pair production of
sneutrinos in $e^+e^-$ collisions and their subsequent decays into two
different charged leptons $e$ and $\mu$ with two lighter charginos. The
analyses are made systematically in a general framework of the supersymmetric
extension of the standard model. The production and decay process depends on
the parameters of the chargino sector, as well as those of the sneutrino
sector. Although generation-changing interactions are severely constrained by
radiative charged-lepton decays, sizable regions in the parameter space could
still be explored at $e^+e^-$ colliders in near future.
