  We search for the lepton flavor-violating "tau -> mu gamma" decay using 29.7
million tau pairs accumulated by the Belle experiment. The main background
sources are found to be tau pairs with "tau -> mu nu nu" decay and radiative
dimuon events. One event is observed in the signal region, while 2.5 +- 0.6
background events are expected. A preliminary upper limit Br(tau -> mu gamma) <
6 x 10^{-7} at the 90% confidence limit is obtained.
