Charged Higgs mass bound from the b to s γ process in the minimal supergravity

The constraint on the mass of the charged Higgs boson from the recent measurement of the inclusive $b \rightarrow s \gamma$ decay is studied in a framework of the minimal supergravity. It is shown that the lower bound for the charged Higgs mass crucially depends on the sign of the higgsino mass parameter ($\mu$). For $\mu<0$, the bound exceeds 400 GeV when the ratio of two Higgs vacuum expectation values ($\tan\beta$) is larger than 10. No strong bound is obtained for $\mu>0$ due to cancellations between charged Higgs and supersymmetric particle contributions.