SUSY-GUT Higgs Probe at Future $e^{+}{e}^{-}$ Colliders

Several independent constraints on the minimal supersymmetric model with constraints from grand unifications and cosmology select the region of low-energy supersymmetry below $\mathcal{O}$(1~TeV). The resulting mass of the lightest Higgs boson can probably be covered at LEP II only if its beam energy exceeds 200~GeV, and is within the detectability range of the NLC with $\sqrt{s}=300$~GeV.