Instanton Contribution to B rightarrow X_(s) γ Decay

We study instanton effects on $B \rightarrow X_s\gamma$ decay using the heavy quark effective field theory and the operator product expansion. In the dilute gas approximation the effect is negligibly small. This is in contrast to the result of the instanton effect in inclusive semileptonic $b\rightarrow u$ decay but similar to the inclusive hadronic $\tau$ decay. We discuss the similarities and differences of the $B \rightarrow X_s\gamma$ decay compared to inclusive hadronic $\tau$ decay and semileptonic $B$ decay.