$b\to s γ$ Decay in the Two Higgs Doublet Model

QCD corrections to $b \to s \gamma$ decay in the two Higgs doublet model are calculated from the energy scale of top quark to that of bottom. The constraints on the two Higgs doublet model from the new experimental bounds of $b\to s\gamma$ by CLEO and the latest top quark mass by CDF and D0 are reanalyzed. It shows that the constraints become more stringent than that of the earlier analysis, i.e. a bigger region of the parameter space of the model is ruled out.