  We study the lepton flavor violating $\mu^- \to e^{-}2\gamma $ decay induced
by the mediation of heavy leptons such as the excited and fourth generation
leptons. We have examined the effects of these leptons in the $\mu^- \to
e^{-}2\gamma $ decay. We have found that branching ratio of this decay is very
sensitive to excited and fourth generation leptons. Furthermore, we have
obtained the bounds on model parameters by using the current experimental limit
of this decay.
