  Electroweak baryogenesis depends on the profile of the bubble wall created in
the first-order phase transition. It is pointed out that CP violation in the
Higgs sector of the MSSM could become large enough to explain the baryon
asymmetry. We confirm this by solving the equations of motion for the Higgs
fields with the effective potential at the transition temperature. That is, we
present an example such that the transitional CP violation is realized and show
the possibility that the baryon asymmetry of the universe may be produced, if
marginally, by the $\tau$ lepton interacting with the wall, when an explicit CP
breaking in the Higgs sector, which is consistent with experimental bounds, is
induced at the phase transition.
