  CP violation in semileptonic top-quark decay is investigated by exactly using
one charged- and three neutral-Higgs bosons obtained by solving the Higgs mass
matrix in two-Higgs doublet model. The CP-violating up-down asymmetry of
leptons from $W$ boson decays is shown to be $1 \times 10^{-4} - 4 \times
10^{-3}$ for the region of ${\rm tan} \beta \ll 1$, where ${\rm tan} \beta $ is
the ratio of vacuum expectation values for the two neutral Higgs bosons.
