  We study $\mu$ and $B$-parameters in the minimal supersymmetric standard
model (MSSM) based on the radiative electroweak symmetry breaking scenario
using $\lq\lq$bottom-up" approach and show how useful our approach is to select
a phenomenologically viable model beyond the MSSM under the assumption that the
underlying theory is a string model or a gauge-Yukawa unified gauge model.
