  We analyze lepton flavor violating $\tau \to \mu \gamma$ and $\mu \to e
\gamma$ processes in SUSY GUT model in which sfermions have special mass
spectrum. It is assumed that only third generation sfermions which are
contained in ${\bf 10}(Q, U^c, E^c)$ of SU(5) can have a different mass from
the others. This mass spectrum is led from $E_6$ GUT model with horizontal
symmetries. It is shown that branching ratios of $\tau \to \mu \gamma$ and $\mu
\to e \gamma$ depend strongly on a right-handed stau mass. The weak scale
stability requires the light stau, so large decay rates can be expected in this
scenario. When stau is around 150 GeV and $\tan \beta \sim 10$, the branching
ratios can be larger than $Br(\tau \to \mu \gamma) \simeq 10^{-8}$ and $Br(\mu
\to e \gamma) \simeq 5\times 10^{-12}$, which are within reach of future
experiments. In addition, this model has an interesting feature that the final
state charged lepton tends to have the right-handed chirality.
