  A phenomenological consequence of electroweak baryogenesis is studied in
connection with the Higgs physics. In a two Higgs double model, the first order
phase transition can be strong enough to allow the electroweak baryogenesis due
to the effect of extra Higgs bosons. We investigate the quantum correction to
the triple coupling of the lightest Higgs boson in such a scenario, and find
that the condition of the strong first order phase transition necessarily leads
to the deviation of at least 10 percent from the standard model prediction.
Such magnitude of the deviation can be identified in future $e^+e^-$ linear
collider experiments. We also discuss the minimal supersymmetric standard model
with the light stop scenario, and point out that a sizable correction appears
in the triple coupling for successful electroweak baryogenesis.
